Clutched Joint Modules Having a Quasi-Passive Elastic Actuator for a Robotic Assembly

ABSTRACT

A method for operating a robotic joint of a robotic system comprising selectively operating a clutch mechanism of a clutched joint module in an engaged state to cause a quasi-passive elastic actuator to enter an elastic state, the clutched joint module operating about and defining a joint of the robotic system. The method comprising effecting a first rotation of the joint to cause the quasi-passive elastic actuator to store energy during at least a portion of the rotation of the joint. The method comprising effecting a second rotation of the joint and causing the stored energy from the quasi-passive elastic actuator to be released in the form of an augmented torque applied to an output member of the clutched joint module. The method comprising selectively operating the clutch mechanism in a disengaged state to cause the quasi-passive elastic actuator to enter an inelastic state. The method comprising effecting a third rotation of the joint, wherein the quasi-passive elastic actuator facilitates a free swing mode of the clutched joint module and the joint.

RELATED APPLICATIONS

This is a divisional application of U.S. application Ser. No.17/087,544, filed Nov. 2, 2020, entitled “Clutched Joint Modules Havinga Quasi-Passive Elastic Actuator for a Robotic Assembly”, which is adivisional application of U.S. application Ser. No. 15/810,102, filedNov. 12, 2017, entitled “Clutched Joint Modules Having a Quasi-PassiveElastic Actuator for a Robotic Assembly”, which claims the benefit ofU.S. Provisional Application Ser. No. 62/421,175, filed Nov. 11, 2016,each of which is incorporated by reference herein in its entirety.

BACKGROUND

A wide variety of exoskeleton, humanoid, robotic arms, and other robotsand robotic systems exist, many of which seek the most efficientoperation possible. One fundamental technical problem that continues tobe a focus is how such systems, such as where energetic autonomy isconcerned, can minimize power consumption while still providingacceptable levels of force output. Indeed, power remains an inevitablechallenge in the world of robotics. Designers of such systems typicallyattempt to optimize operation based on the intended use or application.In many cases, either power or efficiency is sacrificed, at least tosome extent. For instance, some robotic systems employ high-output powersystems that can meet the force output demands of the robotic system,putting this ahead of any efficiency considerations. On the other hand,some robotic systems employ more efficient power systems in an attemptto improve efficiency, with force output being a secondaryconsideration. High output force or power systems, while capable ofperforming various tasks, can be costly. Moreover, such systems oftenare tethered to a power source as portable power remains limited in itscapabilities. Efficient, yet low force output systems can lackpracticality, inasmuch as many robotic systems are designed to assisthumans in work related or other tasks that require a certain level offorce in order to perform the task(s). Overall, the power issue has beena challenging obstacle with various efforts being made to maximizeoutput while minimizing power consumption. Even small advances in thisratio of power to output energy consumption area can be highlybeneficial. While much research and development is ongoing to improvepower sources, another way robotic systems can improve the power toenergy output ratio is through the structural build of the roboticsystem, namely the way various components are configured, how these arecontrolled, and if the systems can take advantage of naturally occurringphenomenon, such as gravity.

BRIEF SUMMARY OF THE INVENTION

An initial summary of the disclosed technology is provided here.Specific technology examples are described in further detail below. Thisinitial summary is intended to set forth examples and aid readers inunderstanding the technology more quickly, but is not intended toidentify key features or essential features of the technology nor is itintended to limit the scope of the claimed subject matter.

The present disclosure sets forth a clutched joint module of a roboticassembly, comprising an output member operable to couple to a firstsupport member of a robotic system; an input member operable to coupleto a second support member of the robotic system; a primary actuatoroperable to apply a primary torque to the output member to rotate thefirst and second support members relative to one another about an axisof rotation of the clutched joint module; a quasi-passive elasticactuator coupled to the input member and operable to apply an augmentedtorque to the output member that combines with the primary torqueapplied by the primary actuator to rotate the output member about theaxis of rotation; and a clutch mechanism operably coupled to the primaryactuator and the quasi-passive elastic actuator, the clutch mechanismoperable in an engaged state and a disengaged state, wherein, in theengaged state, the clutch mechanism operates to place the quasi-passiveelastic actuator in an elastic state, and to facilitate application ofthe augmented torque.

In the disengaged state, the clutch mechanism can operate to place thequasi-passive elastic actuator in an inelastic state.

The quasi-passive elastic actuator can comprise an elastic component inthe form of a mechanical elastic component. The mechanical elasticcomponent can comprise a torsional coil spring.

The primary actuator can comprise a primary axis of rotationsubstantially collinear with the axis of rotation of the clutched jointmodule.

The clutch mechanism can comprise a clutch axis of rotationsubstantially collinear with the axis of rotation of the clutched jointmodule.

The clutched joint module can further comprise a transmission operableabout the axis of rotation of the clutched joint module, wherein thetransmission is operably coupled between the primary actuator and theoutput member.

The clutch mechanism, the primary actuator, and the transmission can allarranged and operable about the axis of rotation of the clutched jointmodule.

The transmission can be at least partially disposed within a centralvoid of the primary actuator.

At least one of the clutch mechanism or quasi-passive elastic actuator,in the elastic state, can operate as a brake to restrict rotationbetween the input and output members.

The clutch mechanism can comprise a rotary transfer component coupled tothe primary actuator; an engagement ring coupled to the torsional coilspring; a movable engagement component coupled to the input member andengaged with the engagement ring; and a clutch actuator coupled to themovable engagement component and operable to translate the movableengagement component to engage the rotary transfer component with theengagement ring to cause the clutch mechanism to function in the engagedstate to facilitate application of the augmented torque.

The engagement ring can surround the torsional coil spring, whereinengagement features of the movable engagement component can engage withengagement features of the engagement ring.

Upon a first rotation of the input member with the clutch mechanism inthe engaged state, the torsional coil spring can be operable to storeenergy, and upon a second rotation of the input member with the clutchmechanism maintained in the engaged state, the torsional spring can beoperable to release energy to apply the augmented torque, and whereinupon a third rotation of the input member, the clutch actuator isoperable to disengage the movable engagement component from the rotarytransfer component to disengage the clutch mechanism, and to place thequasi-passive elastic actuator in the inelastic state to facilitateremoval of the augmented torque. The first, second and third rotationscan be in the same direction, or different directions.

The clutch mechanism can further comprise a splined shaft rotatablycoupled to the rotary transfer component and coupled to the torsionalcoil spring; and a splined collar coupled to the splined shaft, whereinthe clutch actuator is coupled to the splined collar by a transmissionbelt operable to rotate the splined collar, thereby causing translationof the movable engagement component between an engaged state anddisengaged state with respect to the rotary transfer component.

The primary actuator can comprise an electric motor having a centralvoid, wherein the clutched joint module can further comprise a firsttransmission at least partially disposed within the central void; and asecond transmission operatively coupled between the first transmissionand the output member.

The electric motor, the rotary transfer component, the engagement ring,the movable engagement component, and the first and second transmissionscan each rotate about the axis of rotation of the clutched joint module.

The rotary transfer component can be coupled to a rotor of the electricmotor and to the first transmission, such that the rotary transfercomponent transfers the primary torque from the electric motor to thefirst transmission.

The clutch mechanism can further comprise a semi-engaged state, theclutch mechanism comprising a clutch housing coupled to the inputmember; a plurality of input plates retained by the clutch housing; aplurality of output plates rotatably supported by the clutch housing androtatably interfaced with the plurality of input plates in analternating manner; and an electromagnetic actuator coupled to theclutch housing and operable to apply selective, variable compression tothe output plates and the input plates to cause the clutch mechanism tofunction in the engaged or semi-engaged state where at least one of abraking force is generated or the augmented torque is applied to theoutput member.

The clutch mechanism can further comprise a clutch output shaft coupledto the output plates and freely movable relative to the input plates,such that, when the clutch mechanism is in the disengaged state, theoutput plates freely rotate relative to the input plates.

The quasi-passive elastic actuator can comprise an elastic component inthe form of a torsional coil spring, wherein one end of the torsionalcoil spring is coupled to a transfer shaft coupled to the clutch outputshaft and coupled to the primary actuator, and wherein the other end ofthe torsional coil spring is coupled to the input member.

The primary actuator can comprise an electric motor, and the clutchedjoint module can further comprise a transmission operatively coupled tothe electric motor and the transfer shaft.

The electric motor, the transfer shaft, the clutch output shaft, and thetransmission can each rotate about the axis of rotation of the clutchedjoint module.

The present disclosure sets forth a robotic system for minimizing powerconsumption of the robotic system, comprising a plurality of supportmembers; and a plurality of clutched joint modules, each rotatablycoupling together at least two of the plurality of support members, eachclutched joint module comprising a joint rotatable about an axis ofrotation and defining a degree of freedom of the robotic system; aprimary actuator operable to apply a primary torque to rotate the joint;a quasi-passive elastic actuator operable to apply an augmented torquethat combines with the primary torque from the primary actuator torotate the joint; and a clutch mechanism coupled to the primary actuatorand the quasi-passive elastic actuator, the clutch mechanism operable inan engaged state and a disengaged state, wherein, in the engaged state,the clutch mechanism operates to place the quasi-passive elasticactuator in an elastic state, and to facilitate application of theaugmented torque.

With regards to the system, the clutch mechanism can comprise a clutchaxis of rotation substantially collinear with the axis of rotation ofthe joint.

The system can further comprise a transmission operable about the axisof rotation of the joint, wherein the transmission is at least partiallydisposed within a central void of the primary actuator.

A first clutched joint module of the plurality of the plurality ofquasi-passive joint modules can comprise a quasi-passive elasticactuator having a type of an elastic component different from a type ofan elastic component of a quasi-passive elastic actuator of a secondclutched joint module of the plurality of clutched joint modules.

The clutch mechanism can further comprise a semi-engaged state, and theelectromagnetic actuator can be operable to apply selective, variablecompression to the output plates and the input plates to cause theclutch mechanism to function in the engaged or semi-engaged state whereat least one of a braking force is generated or the augmented torque isapplied to the output member.

The present disclosure further sets forth a method for operating arobotic joint of a robotic system, the method comprising selectivelyoperating a clutch mechanism of a clutched joint module in an engagedstate to cause a quasi-passive elastic actuator to enter an elasticstate, the clutched joint module operating about and defining a joint ofthe robotic system; effecting a first rotation of the joint to cause thequasi-passive elastic actuator to store energy during at least a portionof the rotation of the joint; effecting a second rotation of the jointand causing the stored energy from the quasi-passive elastic actuator tobe released in the form of an augmented torque applied to an outputmember of the clutched joint module; selectively operating the clutchmechanism in a disengaged state to cause the quasi-passive elasticactuator to enter an inelastic state; and effecting a third rotation ofthe joint, wherein the quasi-passive elastic actuator facilitates a freeswing mode of the clutched joint module and the joint. The first, secondand third rotations can be in the same direction, or differentdirections.

The method can further comprise selectively operating the clutchmechanism in the engaged and disengaged states to switch thequasi-passive elastic actuator between elastic and inelastic states,respectively.

Effecting at least one of the first, second or third rotation of thejoint can comprise operating a primary actuator to apply a primarytorque to the output member.

Effecting at least one of the first, second or third rotation of thejoint can comprise receiving a force applied about the joint from anexternal source sufficient to induce the rotation.

The method can further comprise transferring the primary torque from theprimary actuator to a transmission to actuate the clutched joint module.

The quasi-passive actuator can comprise an elastic component in the formof a torsional coil spring.

The method can further comprise operating a clutch actuator of theclutch mechanism to cause a movable engagement component to engage oneor more engagement features of an engagement ring coupled to thetorsional coil spring, thereby causing the clutch mechanism to enter theengaged state to activate the quasi-passive elastic actuator.

The clutch mechanism can further comprise a semi-engaged state, themethod can further comprise selectively operating an electromagneticactuator to generate a variable electromagnetic field to apply avariable compression force to a plurality of plates in the clutchmechanism, thereby causing the clutch mechanism to enter one of theengaged or semi-engaged states where at least one of a braking force isgenerated or the augmented torque is applied to the output member.

The present disclosure further sets forth a clutched joint module foruse within a robotic assembly, comprising an output member operable tocouple to a first support member of a robotic system; an input memberoperable to couple to a second support member of the robotic system; aprimary actuator operable to apply a primary torque to the output memberto rotate the first and second support members relative to one anotherabout an axis of rotation of the clutched joint module, wherein theprimary actuator and the output member are operatively coupled to eachother by a torque transfer device; a quasi-passive elastic actuatorcoupled to the input member and operable to apply an augmented torque tothe output member that combines with the primary torque applied by theprimary actuator to rotate the output member about the axis of rotation;and a clutch mechanism operably coupled to the primary actuator and thequasi-passive elastic actuator, the clutch mechanism operable in anengaged state and a disengaged state, wherein, in the engaged state, theclutch mechanism operates to place the quasi-passive elastic actuator inan elastic state, and to facilitate application of the augmented torque.

The clutch mechanism and the primary actuator can each have a centralaxis of rotation substantially parallel to each other.

The quasi-passive elastic actuator can comprise a torsional coil spring.

The clutch mechanism can comprise a rotary transfer component coupled tothe primary actuator; an engagement ring coupled to the torsional coilspring; a movable engagement component coupled to the input member andengaged with the engagement ring; and a clutch actuator coupled to themovable engagement component and operable to translate the movableengagement component to engage the rotary transfer component with theengagement ring to cause the clutch mechanism to function in the engagedstate to facilitate application of the augmented torque.

The engagement ring can surround the torsional coil spring, andengagement features of the movable engagement component can engage withengagement features of the engagement ring.

Upon a first rotation of the input member with the clutch mechanism inthe engaged state, the torsional coil spring can be operable to storeenergy, and upon a second rotation of the input member with the clutchmechanism maintained in the engaged state, the torsional spring can beoperable to release energy to apply the augmented torque, and whereinupon a third rotation of the input member, the clutch actuator can beoperable to disengage the movable engagement component from the rotarytransfer component to disengage the clutch mechanism, and to place thequasi-passive elastic actuator in the inelastic state to facilitateremoval of the augmented torque. The first, second and third rotationscan be in the same direction, or different directions.

The clutch mechanism can comprise a clutch housing coupled to the inputmember; a plurality of input plates retained by the clutch housing; aplurality of output plates rotatably supported by the clutch housing androtatably interfaced with the plurality of input plates in analternating manner; and an electromagnetic actuator coupled to theclutch housing and operable to apply a compression force to the outputplates and the input plates to cause the clutched mechanism to functionin the engaged state to facilitate application of the augmented torque.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the invention will be apparent from thedetailed description which follows, taken in conjunction with theaccompanying drawings, which together illustrate, by way of example,features of the invention; and, wherein:

FIG. 1 illustrates two positions of a robotic assembly in the form of alower exoskeleton having at least one clutched joint module inaccordance with an example of the present disclosure;

FIG. 2A is a schematic illustration of a clutched joint module inaccordance with an example of the present disclosure;

FIG. 2B is a schematic illustration of a clutched joint module inaccordance with an example of the present disclosure;

FIG. 3A is a graph illustrating human weight normalized knee jointtorque vs. knee joint angle of a human gait cycle;

FIG. 3B is a graph illustrating the torque required to accomplish ajoint trajectory and a portion of a gait where an elastic response canbe created by a clutched joint module;

FIG. 3C is a graph illustrating performance of a clutched joint modulein accordance with an example of the present disclosure;

FIG. 4A is an isometric view of a robotic assembly, namely a wearablerobotic exoskeleton, having at least one clutched joint module inaccordance with an example of the present disclosure;

FIG. 4B is an isometric view of the robotic exoskeleton of FIG. 4A;

FIG. 4C a is close-up isometric view of the robotic exoskeleton of FIG.4A;

FIG. 5A is an isometric view of a clutched joint module in accordancewith an example of the present disclosure;

FIG. 5B is an exploded view of the clutched joint module of FIG. 5A;

FIG. 5C is an exploded view of the clutched joint module of FIG. 5A;

FIG. 5D is a cross sectional view of the clutch mechanism of theclutched joint module FIG. 5A;

FIG. 5E is a cross sectional view of the clutch mechanism of theclutched joint module of FIG. 5A, from another perspective;

FIG. 6A is an isometric view of a clutched joint module in accordancewith an example of the present disclosure;

FIG. 6B is an exploded view of the clutched joint module of FIG. 6A;

FIG. 6C is an exploded view of the clutched joint module of FIG. 6A;

FIG. 6D is an exploded view of the clutched joint module of FIG. 6A;

FIG. 6E is an exploded view of a portion of the clutched joint module ofFIG. 6A;

FIG. 6F is a cross sectional exploded view of a portion of the clutchedjoint module of FIG. 6A;

FIG. 6G is a cross sectional exploded view of a portion of the clutchedjoint module of FIG. 6A;

FIG. 7A is an exploded view of a clutched joint module, having theclutch mechanism and quasi-passive elastic actuator of FIG. 5A-5E; and

FIG. 7B is an exploded view of a primary actuator of the clutched jointmodule of FIG. 7A.

Reference will now be made to the exemplary embodiments illustrated, andspecific language will be used herein to describe the same. It willnevertheless be understood that no limitation of the scope of theinvention is thereby intended.

DETAILED DESCRIPTION

As used herein, the term “substantially” refers to the complete ornearly complete extent or degree of an action, characteristic, property,state, structure, item, or result. For example, an object that is“substantially” enclosed would mean that the object is either completelyenclosed or nearly completely enclosed. The exact allowable degree ofdeviation from absolute completeness may in some cases depend on thespecific context. However, generally speaking the nearness of completionwill be so as to have the same overall result as if absolute and totalcompletion were obtained. The use of “substantially” is equallyapplicable when used in a negative connotation to refer to the completeor near complete lack of an action, characteristic, property, state,structure, item, or result.

As used herein, “adjacent” refers to the proximity of two structures orelements. Particularly, elements that are identified as being “adjacent”may be either abutting or connected. Such elements may also be near orclose to each other without necessarily contacting each other. The exactdegree of proximity may in some cases depend on the specific context.

An initial summary of technology embodiments is provided above and thenspecific technology embodiments are described in further detail later.This initial summary is intended to aid readers in understanding thetechnology more quickly but is not intended to identify key features oressential features of the technology nor is it intended to limit thescope of the claimed subject matter.

One example of a robotic assembly 100 is generically illustrated in FIG.1 . The robotic assembly 100 is shown in the form of an exoskeleton, andparticularly a lower exoskeleton wearable by a user about the lowerbody. However, this is not intended to be limiting in any way as theconcepts discussed herein can be applicable to and incorporated into orimplemented with various types of robotic devices, such as exoskeletons(both upper and lower exoskeletons), humanoid robots or robotic devices,teleoperated robots or robotic devices, robotic arms, unmanned groundrobots or robotic devices, master/slave robots or robotic devices(including those operable with or within a virtual environment), and anyother types as will be apparent to those skilled in the art.

In the example of the robotic assembly 100, the exoskeleton as disclosedherein can be configured as a full-body exoskeleton (i.e., similar tothe exoskeleton having both a lower body portion and upper body portion,see FIG. 4A), or as only a lower body exoskeleton (i.e., some or all ofthe lower body portion), or as only an upper body exoskeleton (i.e.,some or all of the upper body portion).

In some examples, the robotic assembly 100 can comprise left and rightexoskeleton limbs. Note that only the right exoskeleton limb 102 isshown in FIG. 1 , but it should be appreciated that the principlesdiscussed can relate to joint modules of any exoskeleton limb of anupper body or lower body exoskeleton. The right exoskeleton limb 102 cancomprise a plurality of lower body support members 104 a-d. The supportmembers 104 a-d can be coupled together for relative movement about aplurality of clutched joint modules 106 a-d defining a plurality ofdegrees of freedom about respective axes of rotation 108 a-d. Therotational degrees of freedom about the axes of rotation 108 a-d cancorrespond to one or more degrees of freedom of the human leg. Forexample, the rotational degrees of freedom about the axes 108 a-d cancorrespond, respectively, to hip abduction/adduction, hipflexion/extension, knee flexion/extension, and ankle flexion/extension,respectively. Similarly, although not shown, rotational degrees offreedom about respective axes of rotation within an upper bodyexoskeleton can correspond to one or more degrees of freedom of a humanarm. For example, the degrees of freedom about the axes of rotation cancorrespond to shoulder abduction/adduction, shoulder flexion/extension,shoulder medial/lateral rotation, elbow flexion/extension, wristpronation/supination, and wrist flexion/extension. A degree of freedomcorresponding to wrist abduction/adduction can also be included, asdesired.

A human user or operator may use or interact with the exoskeletonrobotic assembly 100 (or 101 of FIG. 4A) interfacing with the roboticassembly 100. This can be accomplished in a variety of ways as is knownin the art. For example, an operator may interface with the roboticassembly 100 by placing his or her foot into a foot portion of theassembly, where the foot of the operator can be in contact with acorresponding force sensor. Portions of the human operator can also bein contact with force sensors of the exoskeleton robotic assembly 100located at various locations of the robotic assembly 100. For example, ahip portion of the robotic assembly 100 can have one or more forcesensors configured to interact with the operator's hip. The operator canbe coupled to the robotic assembly 100 by a waist strap, shoulder strapor other appropriate coupling device. The operator can be furthercoupled to the robotic assembly 100 by a foot strap and/or a handle forthe operator to grasp. In one aspect, a force sensor can be locatedabout a hip, knee or ankle portion of the robotic assembly 100,corresponding to respective parts of the operator. While reference ismade to sensors disposed at specific locations on or about the roboticassembly 100, it should be understood that position or force sensors, orboth, can be strategically placed at numerous locations on or about therobotic assembly 100 in order to facilitate proper operation of therobotic assembly 100.

As a general overview, clutched joint modules 106 a-d can be associatedwith various degrees of freedom of the exoskeleton to provide forces ortorques to the support members in the respective degrees of freedom.Unlike traditional exoskeleton systems and devices, the robotic assembly100 can be configured, such that each clutched joint module isconfigured as either an active actuator, or a quasi-passive actuator, asfurther discussed below. As a quasi-passive actuator, a particularclutched joint module (106 a-d) can be configured to recover energy,which can reduce complexity and power consumption of the roboticassembly 100. For example, the clutched joint module 106 c, whichdefines a degree of freedom corresponding to a degree of freedom of kneeflexion/extension, can be configured to recover energy during a firstgait movement and then release such energy during a second gait movementto apply an augmented torque to assist a primary actuator providing aprimary torque in rotation of the joint about the degree of freedom (andin parallel or series with the torque applied by the primary actuator ofthe clutched joint module 106 c, as discussed below). The clutched jointmodule 106 c can be selectively controlled, so as to be engaged (i.e.,caused to enter an operating state or condition in which the elasticactuator stores and releases energy (an elastic state)) and disengagedfrom operation (i.e., caused to enter an operating state or condition orconfiguration where it neither stores nor releases energy (an inelasticstate)), such that the joint “freely swings” with negligible resistanceto rotate the joint as the operator walks or runs, for instance. Byoperating in parallel or series with the primary actuator (e.g., aprimary motor operable to actuate the joint), the quasi-passive elasticactuator can provide or apply an augmented torque in parallel or serieswith the torque provided by the primary actuator (i.e., a torque that isadded to the torque generated by the primary actuator). Thequasi-passive elastic actuator can comprise a compact internal valve,such as a two-way valve, that can be controlled and operated to changethe modes of the quasi-passive actuator, namely to switch between anelastic state (where the actuator acts as a spring for transient energystorage and recovery), and an inelastic state (where the actuatoremploys a shunting function that allows the actuator to move freely(i.e., not to store or release energy) (except for friction and movementof fluid through the valve). And, the clutched joint module 106 c (as aquasi-passive actuator) can be “tuned” to comprise a desired stiffness,which can also be modified, as further discussed below. Thus, themagnitude of stiffness for a given joint is adjustable for missionspecific payloads and terrain-specific gaits while the active valvecontrols exactly when that stiffness is engaged for energy recoveryduring the support phase and when it is disengaged during the freeswinging phase.

As a quasi-passive actuator, the result is effectively a quasi-passiveelastic mechanism that is selectively operable to recover energy (e.g.,energy lost during some gait or other motions) to reduce or minimizepower consumption required to actuate the joint.

The example elastic actuators described herein can be referred to asquasi-passive elastic actuators as they are operable in active andinactive states or modes of operation (as compared to being entirelypassive elastic actuators that are always either storing energy orreleasing energy during all rotational movements of a joint, or othermovements of a mechanical system). In examples described herein, thepassive and inactive modes or states of operation can be selectable orcontrollable and even dynamically selectable or controllable (e.g.,selectable in real-time), as well as repeatedly switched from one stateor mode to another state or mode, during operation of the roboticsystem. Depending upon the configuration of the clutched joint module,example quasi-passive elastic actuators can comprise a first activestate (sometimes referred to herein as an “elastic state”) in which thequasi-passive elastic actuator can be actuated to store and releaseenergy during various rotations of a joint of the robotic system, asecond passive state (sometimes referred to herein as an “inelasticstate”) in which the quasi-passive elastic actuator can be madeinactive, such that energy is neither stored nor released during variousrotations of the joint, and in some cases a third semi-active orpartially active state (sometimes referred to herein as a “semi-elasticstate”) in which the quasi-passive elastic actuator can be partiallyactuated to store and release energy during various rotations of thejoint. In some example robotic systems, the quasi-passive elasticactuator can be switchable between the different modes or states ofoperation as needed or desired depending on, for example, needed ordesired tasks and corresponding rotation movements, various torque orload requirements of the one or more joints of the robotic system, orneeded or desired braking forces.

When combining a plurality of clutched joint modules within a roboticassembly, such as the lower body exoskeleton shown in FIG. 1 or 4A, forexample, a significant amount of energy can be recovered and utilizedduring movement (via hip, knee, and ankle joints), which can reduceweight, size, complexity, and power consumption of the exoskeleton.Moreover, each of the various joint modules in the robotic system orassembly can comprise the same type or a different type of quasi-passiveelastic actuators (or in other words the same type of different types ofelastic components), thus the robotic assembly can be configured foroptimal performance depending upon the particular application or tasksto be carried out. The above general overview is explained in moredetail below. As active actuators (i.e., having no quasi-passive elasticelement), a particular clutched joint module can be selectively operable(i.e., via a clutch mechanism) to be engaged as an active actuator toactuate a joint, and also to provide gravity compensation, as furtherdiscussed below.

FIGS. 2A and 2B each schematically illustrate clutched joint modules inaccordance with two examples of the present disclosure. FIG. 2A shows aclutched joint module 120 having a primary actuator 122 operable toprovide a primary torque to the clutched joint module. In this example,the primary actuator can comprise a motor 124 and a transmission or geartrain 126 (e.g., a planetary transmission) operating in parallel with aclutch mechanism 128 and an elastic element or spring 128 (e.g., aquasi-passive elastic actuator, such as a rotary or linear pneumatic(air or other gas) type of quasi-passive elastic actuator). The primaryactuator 122 is operable to apply a primary torque to a load (e.g., torotate an output member coupled to a robotic support member) in parallelwith an augmented torque selectively applied by the spring(quasi-passive elastic actuator) 128 to rotate a joint of a roboticassembly, as in FIGS. 1 and 4A. The augmented torque is selectivelyapplied by operation of the clutch mechanism 128, which is operablebetween an engaged state and a disengaged state, as further describedbelow. Note that the gear train 126 can be removed or may not be needed,or a supplemental transmission or gear train can be coupled adjacent thegear train 126 to provide a two-stage transmission from the motor 124 tothe load. The examples of FIGS. 5A-5E are schematically represented byFIG. 2A.

FIG. 2B shows a clutched joint module 121 comprising a primary actuator123 comprising a motor 125 and a transmission or gear train 127 (e.g., aplanetary transmission) operating in parallel with a spring 129 andclutch mechanism 131. The clutch mechanism 131 is operable between anengaged state (that facilitates actuation of a primary torque by theprimary actuator 123 to the load) and a disengaged state to selectivelycontrol application of the spring 129. The spring 129 is operable tostore energy and then release energy to apply an augmented torque, inparallel with a primary torque applied by the primary actuator 123, toapply a combined torque to the load (e.g., to rotate an output membercoupled to a robotic support member). Here, the output of the spring 129is coupled between the motor 125 and the gear train 127 (whether coupledto the output of the motor 125 or the input of the gear train 127), suchas disclosed below regarding the example of FIG. 6A.

FIG. 3A is a graph showing joint torque vs. joint position as theseoccur during an example gait of a human, the graph showing the torque(N-m/kg) occurring in the joint relative to or as corresponding to theangle of rotation of the joint. This particular graph is illustrative ofan example torque/angular rotation relationship of a human knee (withoutwearing an exoskeleton), while walking approximately 3 mph on a flatsurface. A first gait movement from point A to point B illustratesstance compression following heel strike, a second gait movement frompoint B to C illustrates stance extension, with the stance phase beingcompleted at point D. A third gait movement between points D, E, F, andA illustrates “double support and leg swing.” Therefore, the “stancephase” is from heel strike (point A) to toe-roll/terminal stance (pointsA to D), where the torque-joint profile has a quasi-elastic behavior(walking and running are similar regarding this quasi-elasticstiffness). During this phase, the knee also acts as a shock absorber.The “swing phase” is from toe-off to heel strike (points E to A), andduring this phase the knee exhibits a quasi-ballistic (passive dynamics)response with some damping during the final extension that occurs beforeheel strike (thus, the knee acts as a controlled damper or shockabsorber).

This characteristic of the human gait is not unique to the knee joint,nor limited to the walking gait, and forms the basis for the clutchedjoint modules discussed herein. Indeed, when reviewing the joint torquevs. position plots of simulated cyclical exoskeleton activities, such aswalking, running, and step climbing, there are periods of time duringthese specific gait motions where elastic energy recovery can beexploited to reduce the requirement for motor torque to run the joint.Thus, the clutched joint modules described herein can be configured toexploit the features of the natural motion of the hip, knee, and ankle,for instance, to minimize demands on powered actuators (e.g.,electric-geared motors) to reduce overall power consumption within therobotics assembly. The clutched joint modules discussed herein can alsobe incorporated into shoulder and elbow joints, for instance, but thesemay be more task-specific than as with the lower body joints, as furtherdiscussed below.

However, the clutched joint modules of lower joints (e.g., hip, knee,ankle) can also be configured to operate based on a specific task (e.g.,lifting a load, sitting and standing, and others), rather than just acyclical operation (e.g., walking or running).

FIG. 3B is a graph showing a standard exoskeleton knee joint torque(N-m) vs. position (deg.) for walking at 3.5 mph with a 50 lb. payload.The plotted “triangular” labeled line (“joint actuation torque”)represents the required overall torque to accomplish the prescribedjoint trajectory, while the plotted “circular” labeled lines (“springreaction torque”) represents the part of the gait where an elasticresponse can by created by a quasi-passive elastic actuator of aclutched joint module. Thus, this spring reaction torque can beexploited to reduce power consumption to actuate a joint, as furtherdetailed below.

FIG. 3C is a graph illustrating performance of an exoskeleton having aclutched joint module with a quasi-passive elastic actuator operating inparallel with a primary actuator, the joint module having a jointstiffness of 7 N-m/degree, associated with the human knee joint, in oneexample. More specifically, the graph shows joint torque (N-m) vs. jointspeed (deg./sec) for walking at 3.5 mph with a 50 lb. payload. Theplotted “triangular” labeled line (“joint actuation torque”) representsthe required overall torque to accomplish the prescribed jointtrajectory (e.g., the torque required to rotate a knee), while theplotted “circular” labeled lines (“spring reaction torque”) representsthe part of the gait where an elastic response can be created byengaging and disengaging the quasi-passive elastic actuator in a timelymanner, as exemplified herein.

As illustrated by this “circular” labeled line, the resulting peaktorque is substantially reduced (approximately 25 N-m) vs. thenormalized torque requirement (approximately 100 N-m) of the“triangular” labeled line. That is, normally (i.e., withoutincorporating a clutched joint module having an elastic actuator) thetorque requirement is peaked at approximately 100 N-m; however, whenincorporating a clutched joint module having an elastic actuator asdisclosed herein, the resulting peak torque can be only approximately 20N-m, thus significantly reducing power requirements for the same gaitcycle and operating conditions. This is because the clutched jointmodule stores energy during a first gait movement (via the quasi-passiveelastic actuator), and then releases that energy during a second gaitmovement to apply an augmented torque that can be applied in parallelwith a torque applied by a primary actuator (e.g., a geared motor) ofthe clutched joint module. Of course, other factors play a role in theseresults, such as weight, payload, etc. In any event, these graphsillustrate that much less on-board power is required by the poweredmotor to appropriately actuate a joint when used in conjunction with aselectively controllable quasi-passive elastic actuator, as furtherexemplified below. The use of a parallel elastic actuator effectivelyreduces the requirement for motor torque as the elastic actuator isengaged and disengaged in a timely manner, such as during specificphases of a gait cycle. Similar plots or graphs can be shown for hipjoints, ankle joints, shoulder joints, and elbow joints. In some cases,the elastic actuator can be engaged full-time for the gait cycles ofthese joints.

FIGS. 4A-4C show isometric views of an exemplary robotic assembly 101 inthe form of an exoskeleton wearable or usable by a human operator. Therobotic assembly 101 could alternatively be a humanoid robot, or otherrobotic assembly as discussed above. As shown, the robotic assembly 101can be configured as a full-body exoskeleton (i.e., an exoskeletonhaving both a lower body portion and an upper body portion). However,this is not intended to be limiting as the exoskeleton can comprise onlya lower body exoskeleton (i.e., some or all of the lower body portion),or only an upper body exoskeleton (i.e., some or all of the upper bodyportion).

The robotic assembly 101 can comprise left and right exoskeleton limbs.The right exoskeleton limb 103 can comprise a plurality of lower bodysupport members 105 a-d. The support members 105 a-c can be coupledtogether for relative movement about a plurality of respective joints107 a-c defining a plurality of degrees of freedom about respective axesof rotation. As described in U.S. patent application Ser. No.15/810,108, filed Nov. 12, 2017, which is incorporated by reference inits entirely herein, the hip joint 107 a and knee joint 107 c can eachcomprise a tunable actuator joint module 109 a and 109 c that cancomprise a tunable quasi-passive elastic actuator, as shown in FIGS. 4Aand 4B, having a rotary air spring device as an elastic element orcomponent. Alternatively, the hip and knee joints 107 a and 107 c caneach comprise a clutched joint module, such as described by the presentdisclosure. Joints 107 b and joint 107 d can also each comprise aclutched joint module 109 b and 109 d, respectively, as describedherein.

Similarly, the right exoskeleton limb 103 b can comprise a plurality ofupper body support members 105 e-h coupled together for relativemovement about a plurality of joints 107 e-h defining a plurality ofdegrees of freedom about respective axes of rotation (see FIG. 4C for acloser view). Each joint 107 e-h can comprise a clutched joint module109 e-h, respectively, as described herein. Notably, as furtherdescribed below, each clutched joint module can be provided in a compactform, meaning that the particular axis of rotation of the joint, joint107 e for instance, is substantially collinear with the primarycomponents, and the axes of rotation of the primary components, of theclutched joint module, clutched joint module 109 e for instance (e.g.,primary actuator, planetary transmission(s), clutch mechanism(s),quasi-passive elastic actuator(s)), these being arranged along andconfigured to be operable about the axis of rotation, as furtherexemplified below. Thus, each clutched joint module can provide aparticular high-torque output in a compact form, such as a clutchedjoint module that is generally cylindrical and that locates the mass ofthe module near to the axis of rotation.

FIGS. 5A-5F illustrate a clutched joint module 200 according to anexample of the present disclosure, which can be incorporated as, or inother words, can comprise or define a joint of a robotic assembly (e.g.,100, 101).

The clutched joint module 200 can comprise a primary actuator 202, aquasi-passive elastic actuator 204 (FIG. 5D), and a clutch mechanism 206operatively coupled to each other, and each situated or arranged alongand operable about an axis of rotation 210. As further detailed below,an input member 208 a and an output member 208 b (FIG. 5A) can bedirectly or indirectly coupled to respective support members of therobotic assembly, which support members are rotatable relative to eachother about the axis of rotation 210 of the joint, which can correspondto a degree of freedom of a human joint. For instance, the clutchedjoint module 200 can be incorporated into the robotic assembly 101 asclutched joint module 109 f of FIG. 4C that defines, at least in part,the joint 107 f comprising a shoulder joint having a flexion/extensiondegree of freedom. Note that input and output members 208 a and 208 bare shown generically as members coupled to their respective components,but they can take many different forms and configurations of suitableinput and output members or components that are coupleable to roboticsupport members, for instance.

The primary actuator 202 can comprise a motor 212 and, optionally, atransmission, such as a first planetary transmission 214 and, furtheroptionally, a second transmission 216, such as a second planetarytransmission. The motor 212 is operable to apply a primary torque to theoutput member 208 b for rotation about the axis of rotation 210, and thequasi-passive elastic actuator 204 (e.g., one having an elasticcomponent in the form of a torsional coil spring) is selectivelyoperable to store energy, such as during a first rotation of the jointmodule 200, and to release energy in the form of augmented torque to beapplied to the output member 208 b along with the primary torque appliedby the motor 212 (the two torques being combined to generate an outputvia the output member 208 b).

The clutch mechanism 206 is operable to selectively control thequasi-passive elastic actuator 204 and the generation of the brakingforce or application of the augmented torque. Indeed, a braking forcecan be generated to restrict rotation of the joint in some operationalscenarios (e.g., scenarios where the primary actuator is active or notactive to produce a primary torque, but where rotation of the joint isdesired), or an augmented torque can be generated and applied incombination with a primary torque to assist in rotation of the outputmember and the joint, as discussed below.

With reference to FIGS. 5A-5C, a first support frame 215 a and a secondsupport frame 215 b can be coupled together (via fasteners not shown)and can retain and support the motor 212 and the first planetarytransmission 214, and can support the clutch mechanism 206.

As further detailed below, the quasi-passive elastic actuator 204 isoperable to selectively apply an augmented torque or to generate abraking force (when in an elastic configuration or mode or state) upon arotation of the input member 208 a (e.g., where the rotation is eitheractively carried out using the primary actuator, or passively carriedout, such as rotation of a joint under the influence of gravity of someother externally applied force that induces rotation) when the clutchmechanism 206 is in the engaged state, and is operable to selectivelyrelease energy (also when in the elastic configuration or mode or state)upon a rotation of the input member 208 a (in the same or a differentdirection as the rotation for storing the energy), when the clutchmechanism 206 is in the engaged state, to apply an augmented torque tothe output member 208 b in parallel with the primary torque applied bythe primary actuator 202, in this case the motor 212. The quasi-passiveelastic actuator 204 is further operable to neither store nor releaseenergy (when in an inelastic configuration or mode or state) when theclutch mechanism 206 is selected to be in the disengaged state. In thisinelastic state, the input member 208 a is in “free swing” relative tothe output member 208 b, meaning that negligible resistance is appliedwithin the clutched joint module 200 via the quasi-passive elasticactuator 204 (so that the quasi-passive elastic actuator 204 does nothave a stiffness value that would restrict rotation of the input member208 a relative to the output member 208 b). The clutch mechanism 206 canalso move from an engaged state to a disengaged state to dissipate anystored energy (i.e., dissipate any braking force generated, such as whenthe braking force no longer needed). Thus, the quasi-passive elasticactuator 204 is selectively switchable between the elastic state and theinelastic state via operation of the clutch mechanism 206. One advantageis that the quasi-passive elastic actuator 204 can be caused to apply,at select times, an augmented torque in parallel with the primary torqueapplied by the motor 212, which therefore applies a combined torque torotate the output member 208 b, thereby reducing the powerrequirements/demands of the motor 212. With the advantage of anaugmented torque, the motor 212 selected can be of a smaller size and alower power dissipation than otherwise would be required by a systemwithout the assistance of the augmented torque provided by thequasi-passive elastic actuator 204. Note that the quasi-passive elasticactuator 204 and the clutch mechanism 206 can be “coupled to” the inputmember 208 a as shown, or at any point between various componentssituated between the input and output members, such as between the motor212 and the output member 208 b (and between or adjacent any one of thetransmissions).

In examples described herein, “selective” can mean that the clutchedjoint module can be controlled in real-time, such as to vary a magnitudeand timing of a braking force, vary a magnitude and timing ofcompression of the elastic component of the quasi-passive actuator andthe storing and releasing of energy therein, or vary a magnitude andtiming of a primary torque generated by the primary actuator dependingupon different operating conditions, operating states, different demandsof the robotic system, or as desired by the operator. Selective controlcan mean that the quasi-passive elastic actuator can be operated inconjunction with the primary actuator all or some of the time or for adesired duration of time. In addition, “selective” can also mean, inexamples, that one or more operating parameters or the outputperformance of the clutched joint module can be controlled and varied inreal-time as needed or desired. Operating parameters or outputperformance can include, but is/are not limited to, a magnitude of theaugmented torque to be applied, a magnitude of the braking forcegenerated, the stiffness or elasticity of the elastic actuator, the zeroor null point of actuation of the elastic actuator, and others.

In one example, the motor 212 is a high-performance Permanent MagnetBrushless DC motor (PM-BLDC), which can be a variant of a framelesstorque motor with winding optimized to achieve the desired maximumtorque and speed while operating using a 48 VDC supply and ahigh-performance COTS controller, such as electric motor MF0127-032marketed by Allied Motion.

With reference to FIG. 5B, the motor 212 can comprise a stator 220 androtor 222 rotatable relative to each other (in a typical fashion forcommercially available frameless brushless motors). Thus, the motor 212of the primary actuator 202 comprises a cylindrical void 224 about thecentral area of the rotor 222. Advantageously, the first planetarytransmission 214 can be positioned (at least partially) within thecylindrical void 224 of the motor 212, which provides a low-profile,compact geared motor configuration because the first planetarytransmission 214 and the motor 212 are packaged together, as shown anddescribed.

In the present example, the first planetary transmission 214 cancomprise a 4:1 geared transmission. Thus, in one example, the firstplanetary transmission 214 can comprise an outer housing 226 attached tothe first support frame 215 a via fasteners (not shown) throughapertures 228 of the outer housing 226. The outer housing 226 comprisesinner gear teeth formed around an inner surface of the outer housing226. Such gear teeth can be configured to engage corresponding gearteeth of each of four planet gears 230 (2/4 labeled). A sun gear 232 canbe disposed centrally between the four planet gears 230 and along theaxis of rotation 210, with the sun gear 232 comprising teeth operable toengage the teeth of each of the four planet gears 230 (see FIGS. 5B and5C).

Here, the outer housing 226 can comprise the stationary component of theplanetary transmission 214, and the planet gears 230 can rotate abouttheir own central axis and around the axis of rotation 210. A carrierplate 234 can be fastened to carrier pins 236 (2/4 labeled) viafasteners 235 (2/4 labeled). The carrier pins 236 can each be rotatablyinterfaced through the hollow tubular body of each planet gear 230. Fourrear bushings 238 can each be coupled to a respective carrier pin 236,and a carrier pin plate 231 can be fastened to the carrier pins 236through the bushings 238 via four fasteners 233 to maintain orientationof the planet gears 230 as they rotate.

The sun gear 232 can be coupled to a rotary transfer component 240 ofthe clutch mechanism 206 (FIGS. 5C-5E). The rotary transfer component240 can comprise a central coupling portion 242 that interfaces with thesun gear 232. The rotary transfer component 240 can be coupled to therotor 222 of the motor 212 by fasteners (not shown) about a perimeter ofthe rotary transfer component 240. Therefore, upon receiving a controlsignal, the rotor 222 drives/rotates the rotary transfer component 240,which drives/rotates the sun gear 232, which drives/rotates the carrierplate 234 (via planet gears 230 and carrier pins 236). The carrier plate234 then drives/rotates a sun gear 246 of the second planetarytransmission 216 (FIG. 5B), which ultimately drives/rotates the outputmember 208 b via the planet gears 243 and the carrier 244 of the secondplanetary transmission 216.

Thus, the present example provides a 16:1 final drive transmission fromthe motor 212 to the output member 208 b. Other planetary transmissiontypes and gear reduction schemes can be used instead of a 4:1transmission, such as a 3:1 planetary gear scheme.

To reduce build height, as well as to provide other advantages, thefirst planetary transmission 214 can be configured for positioninginside of the rotor of the motor 212. Depending on the motor selected,the inside diameter of the rotor can dictate the maximum outsidediameter of the planetary transmission. Once the planetary ring has beenconstrained by its outside diameter, there are a limited amount ofoptions for gear ratios and output torques available. The output ratiocan be determined from the ratio of the number of teeth on the ring gearto the number of teeth on the sun gear. To obtain a higher reduction inthe compact design of the planetary unit, the sun gear diameter can bereduced, which generally corresponds to less power transmission. Thecapacity to transmit higher torques is reduced with the smaller sungear. A balance of reduction and strength can be found for a planetaryunit that will physically fit inside the motor rotor. By implementing ahelical cut gear, higher forces can be transmitted on the gear teethmaking the unit stronger. A wider tooth can also improve the loadcarrying capacity of the gear, however this can increase the weight aswell. Multiple stages of a planetary transmission can be cascaded (e.g.,214 and 216) to produce extremely high gear reduction in a relativelycompact package, particularly one about the axis of rotation of thejoint. In addition, the sun gear can make contact with several teethsimultaneously so the contact ratio is much higher than a conventionalspur gear transmission. In some examples, a single stage planetarytransmission can achieve efficiency of around 97%. At higher RPM, gearnoise can be an issue, especially for multiple stage planetary units.Another benefit of the planetary transmission arrangement discussedherein is the fact that the transmission can be located in-line with themotor, which allows for compact mounting configurations within the jointmodule 200 of the robot or robotic assembly. Other examples may locatethe transmission offset from one or more other components of theclutched joint module, with the transmission being operable with theprimary actuator.

As shown in FIGS. 5B and 5C, the motor 212, the first and secondplanetary transmissions 214 and 216, and the output member 208 b caneach operate or rotate about substantially the same axis of rotation asthe axis of rotation 210 of the clutched joint module 200 (i.e., theaxis of rotation of the corresponding joint of the robot or roboticassembly), which axis of rotation in some cases, can also correspond tothe axis of rotation of a human joint, such as an operator in anexoskeleton. Said another way, each axis of rotation of the primaryactuator (e.g., the motor 212), the first and second planetarytransmissions 214 and 216, and the output member 208 b can be arrangedto be collinear or substantially collinear with the axis of rotation210. This locates the mass of such components close or near to the axisof rotation of a particular joint, which further minimizes powerrequirements by the motor 212 to actuate the joint.

It should be appreciated that the planetary transmissions exemplifiedherein can be replaced (or supplemented with) other transmission types,such as harmonic, cycloidal, worm, belt/chain, crank, four-bar linkage,backhoe linkage, bell crank, and continuously variable, for instance.And, various torque-transmitting devices can be operatively coupledbetween the transmissions, such as one or more belts or linkages orgears or tendons (or combinations of such). Moreover, thetransmission(s) can be arranged to have an axis of rotation that isoffset (e.g., oriented in a direction along a plane that is orthogonalor at some other angle) from the axis of rotation of the primaryactuator(s) of the examples of the present disclosure (some otherposition other than collinear). Moreover, various transmissions can bearranged to provide different gear reductions from input to output,including a relatively high gear reduction (e.g., 20:1, or more), or arelatively low gear reduction (e.g., 1:1), or any gear reduction betweenthese, depending on the particular application. In some examples, thetorque-transmitting devices can allow the primary actuator to beremotely located away from the output (i.e., the primary actuator islocated a given distance away from the output of the clutched jointmodule, but operably connected thereto via the torque-transmittingdevice), wherein the remotely located primary actuator can be actuatedand its torque transferred to the output of the tunable actuatable jointmodule corresponding to a joint of the robotic system. For instance, theprimary actuator 202 could be located at a lower back area of anexoskeleton (e.g., FIG. 4A), while such alternative torque-transmittingdevice(s) could transfer the primary toque from the lower back area toan output member located in the clutched actuator joint module for thehip joint for actuating the hip joint.

With particular reference to FIGS. 5B-5E, as introduced above thequasi-passive elastic actuator 204 is operable to apply an augmentedtorque to rotate the output member 208 b, along with the primary torqueapplied by the primary actuator 202. Thus, the quasi-passive elasticactuator 204 is switchable between an elastic configuration and aninelastic configuration via operation of the clutch mechanism 206 forselectively controlling application of the augmented torque applied bythe quasi-passive elastic actuator 204. The quasi-passive elasticactuator 204 is also operable to generate a braking force that canrestrict rotation in the joint between the input and output members.This can also be selectively controlled and varied via the clutchmechanism 206.

The quasi-passive elastic actuator 204 can comprise an elastic elementin the form of a mechanical elastic component or spring. As in theexample shown, the elastic element can specifically comprise a torsionalcoil spring that stores mechanical energy when loaded. In this example,the clutch mechanism 206 can comprise the rotary transfer component 240(coupled to the motor 212, as discussed above) that comprises a centralshaft 248 that is rotatably interfaced through an opening of a splinedshaft 250. The splined shaft 250 includes a male helical splined profilethat interfaces with a female helical splined profile of a splinedcollar 252. The splined collar 252 is fastened to a movable engagementcomponent 254, and rotatably coupled to a clutch actuator 256 (e.g.,electric motor) via a transmission belt 258.

The movable engagement component 254 comprises inner teeth or engagementfeatures 260 formed annularly around the inside of a perimeter wall ofthe movable engagement component 254. The inner teeth or engagementfeatures 260 are engaged to outer teeth or engagement features 262 of anengagement ring gear 264, which is coupled to the quasi-passive elasticactuator 204 in the form of the torsional coil spring. In this manner,one end of the quasi-passive elastic actuator 204 is attached to aninner surface of the engagement ring 264, and the other end of thequasi-passive elastic actuator 204 is attached to the splined shaft 250.The input member 208 a can be coupled to the movable engagementcomponent 254. Accordingly, rotation of the input member 208 a about theaxis of rotation 210 causes rotation of the movable engagement component254 (whether the clutch mechanism 206 is engaged or disengaged). Notethat the various teeth or engagement features can comprise variousshapes and forms, such as protrusions that selectively engage withrespective recessed portions of adjacent parts or components as shown.In one example, the rotary transfer component, the engagement ring, andthe moveable engagement component may not have teeth or protrusions thatengage with each other as described; instead, such components can beformed as plates having a particular shape that, when moved, engage witheach other to lock up or bind up, similar to the plates discussed belowregarding FIG. 6A.

FIGS. 5D and 5E show the clutch mechanism 206 in the disengaged state.In this manner, the inner teeth or engagement features 260 of themovable engagement component 254 are only engaged with the outer teethor engagement features 262 of the engagement ring 264 (i.e., away fromouter teeth or engagement features 266 of the rotary transfer component240). Thus, the input member 208 a, the movable toothed engagementcomponent 254, and the engagement ring 264 freely rotate relative to therotary transfer component 240 in this disengaged state. Therefore, theclutched joint module 200 is in a “free swing” mode as the input member208 a is freely rotatable relative to the output member 208 b. To movethe clutch mechanism 206 to the engaged state (thereby activating thequasi-passive elastic actuator 204 in the elastic state to store and/orrelease energy), the clutch actuator 256 receives a clutch controlsignal from a controller, which causes the clutch actuator 256 to rotatethe transmission belt 258 in the clockwise direction, which causesclockwise rotation of the splined collar 252. Such clockwise rotation ofthe splined collar 252 causes the splined collar 252 to axiallytranslate toward the movable engagement component 254 because of themale helical splined profile of the splined shaft 250. Such axialmovement biases or pushes the movable engagement component 254 axiallytoward the rotary transfer component 240. Upon such axial movement ofthe movable engagement component 254, the inner teeth or engagementfeatures 260 of the movable engagement component 254 engage with theouter teeth or engagement features 266 of the rotary transfer component240. Such engagement results in an indirect, locking engagement of theengagement ring 264 with the rotary transfer component 240, such thatthey can rotate together in the same direction and at the same speed.Thus, the clutch mechanism 206 is caused to be in the engaged state, andthe quasi-passive elastic actuator 204 in the elastic state, whereinrotation of the joint module 200 causes the torsional coil spring to bewound, in which case energy is stored, and unwound, where the storedenergy is released. As the torsional coil spring is caused to unwind,energy from the torsional coil spring is released, an augmented torqueapplied by the torsional coil spring, for instance, is translated to theengagement ring 264, and then to the movable engagement component 254,and then to the rotary transfer component 240, and then to the sun gear232 of the first planetary transmission 214 (FIGS. 5B and 5C), and so on(as described above), to rotate the output member 208 b. Engaging theclutch mechanism 206, and winding of the torsional coil spring can alsobe used to generate a braking force that can be used to restrictmovement of the output member relative to the input member. For example,upon rotation of the joint (either using the primary actuator or inresponse to an external force, such as gravity or a force impacting therobotic system) the clutch mechanism 206 can be engaged to actuate thequasi-passive actuator, wherein this will generate a braking force thatrestricts rotation of the joint. Furthermore, once stored, the energycan be dissipated (by disengaging the clutch mechanism 206) or released(by keeping the clutch mechanism 206 engaged) to apply an augmentedtorque that can be combined with a primary torque, as discussed herein.

Accordingly, while the clutch mechanism 206 is in the engaged state, thequasi-passive elastic actuator 204 can store energy and/or releaseenergy as it is in its elastic state. Specifically, assume the torsionalcoil spring is wound in the clockwise direction from its central area,so that, upon a first clockwise rotation of the input member 208 a aboutthe axis of rotation 210, the quasi-passive elastic actuator 204 (e.g.,torsional coil spring) stores energy. Such rotational movement can bethe result of a gait movement of the robotic assembly (e.g., of a lowerbody exoskeleton) that causes a first robotic support member (e.g., 104e) to rotate about a second robotic support member (e.g., 104 d), suchas during a gait cycle between point B to C as shown in FIG. 2 . Upon asecond counterclockwise rotation (e.g., of 104 e and 104 d betweenpoints A to B of FIG. 2 ), the quasi-passive elastic actuator 204 canrelease its stored energy, thereby transferring an augmented torque toassist in rotation of the output member 208 b, as detailed above. Thedescribed joint rotational directions and when energy is stored andreleased is not intended to be limiting as the clutch mechanism 206 cancontrol the compressing of the elastic component within thequasi-passive elastic actuator to store and release energy in oppositejoint rotation directions or in the same joint rotation direction.

Concurrently, the motor 212 of the primary actuator 202 can be operatedto apply a primary toque (along with the augmented torque) to rotate theoutput member 208 b about axis of rotation 210 to actuate the clutchedjoint module 200. Because the torque applied by the motor 212 issupplemented with the torque applied by releasing stored/recoveredenergy via the quasi-passive elastic actuator 204, the electric motor212 can be selected from a group of smaller (e.g., less powerdissipation) motors than would otherwise be needed, which contributes tothe compact configuration of the clutched joint module 200, as alsodiscussed above.

Upon a rotation of the input member 208 a relative to the output member208 b (either clockwise or counterclockwise), the clutch actuator 256can receive a clutch control signal that causes it to rotate the splinedcollar 252 in the counterclockwise direction, thereby pulling (i.e.,axially translating) the movable engagement component 254 away from therotary transfer component 240, which disengages the engagement ring 264from the rotary transfer component 240. This causes the clutch mechanism206 to be in the disengaged state (as shown on FIGS. 5D and 5E). As aresult, the quasi-passive elastic actuator 204 neither stores norreleases energy (i.e., the quasi-passive elastic actuator 204 enters theinelastic configuration or state), wherein negligible resistance isapplied by the quasi-passive elastic actuator 204 so that the clutchedjoint module 200 does not have a stiffness value restricting rotation ofthe input member 208 a relative to the output member 208 (except for theresistance imparted by the gears of the planetary transmissions, forinstance).

Various sensors, such as position sensors, force sensors, or both, canbe operable within the joint module 200 to determine and measure apositon or a force of the joint module 200, such that the quasi-passiveactuator 204 can be engaged and disengaged as needed or desired. In oneexample, a position sensor 261 can be coupled to the splined collar 252to determine the position of the coupled movable engagement component254, which assists to determine to the position of the input member 208a relative to the output member 208 b. Other position sensors can beincorporated with the joint module 200 to assist with suchdetermination. Thus, each of such first, second, and third rotationalmovements of the input member 208 a relative to the output member 208 b(e.g., of a robotic joint) can be sensed by one or more position and/orforce sensors (e.g., 261) associated with and/or coupled to the clutchedjoint module 200 to sense a direction, speed, and/or force associatedwith rotation of the clutched joint module 200. The one or more sensorscan be coupled at various locations, such as at or near the input member208 a and/or output member 208 b, at the transfer wheel 198, and/orother suitable locations of the clutched joint module 200. In oneexample, a particular position sensor 261 (e.g., Hall effect sensor) cansense a relative position of the input member 208 a, and, upon thesecond rotation (discussed above), the position sensor 261 cancommunicate a position signal to a computer control system, having acentral processing unit, that processes the position signal, and thenultimately transmits an appropriate clutch signal to the clutch actuator265 to engage (or maintain engagement of) the clutch mechanism 206 (forinstance), and/or transmits a primary actuator signal to the motor 212to apply the primary torque, as discussed further herein.

In an example where the joint module 200 is incorporated as a shoulderjoint (e.g., 109 f) of an arm of an exoskeleton (FIG. 4A), assume ahuman operator wearing the exoskeleton desires to lift a 200 poundpayload. As the operator moves the arm downwardly to reach and grab thepayload (e.g., the first rotation of the shoulder joint), the clutchmechanism 206 can be controlled to enter the engaged state, such thatthe quasi-passive elastic actuator 204 stores energy during suchrotation of the shoulder joint. Then, as the operator grabs and beginsto lift the payload (i.e., a second rotation of the shoulder joint), theclutch mechanism 206 is maintained in the engaged state, where thequasi-passive elastic actuator 204 is caused to release stored energy(as discussed above) to apply an augmented torque to rotate the outputmember 208 a (i.e., to assist lifting the payload). Concurrently, aprimary control signal can be received by the motor 212, which exerts aprimary torque (as discussed above) to apply a primary torque, alongwith the augmented torque, to rotate the output member 208 b, thusfacilitating the lifting of the load by the exoskeleton. Upon releasingthe payload, the clutch mechanism 206 can be controlled to be operatedto the disengaged state to remove any spring stiffness that may existabout the quasi-passive elastic actuator 204, thereby placing the jointmodule 200 in free swing mode so that the operator can lower the arm toa desired position without resistance or required actuation.

In some examples, the quasi-passive elastic actuator 204 can act as agravity compensation mechanism to resist gravitational forces imposed onthe robotic assembly, such as on an arm of an exoskeleton, so that thehuman operator does not need to use energy to hold the robotic arm at adesired location or orientation. This is because the torsional coilspring, for instance, can exert a counter biasing force away from orthat acts against the gravitational pull (when the clutch is engaged) tomaintain a certain position of the joint and the robotic support memberscoupled thereto (as well as the relevant part of an operator, if any,such as in the case of an exoskeleton).

Note that spring stiffness of the quasi-passive elastic actuator 204 isa function of the size, shape, material, etc. of the torsional coilspring, for instance. Thus, the magnitude of stiffness for a given jointmodule is selectable (e.g., during manufacture and selection of thetorsional coil spring) for mission-specific payloads andterrain-specific gaits (or other movements) while the clutch mechanismcan be controlled and operated to control when in time, or at whatrotational positions/forces during the various rotational movements ofthe joint module 200 that the quasi-passive elastic actuator 204 is tobe engaged for energy recovery/release during the support phase (i.e.,the elastic configuration), for instance, and when it is disengaged soas to enter the free swinging phase (i.e., the inelastic configuration).Moreover, due to the nature of torsional coil springs, for instance, thegreater the degree of rotation during energy storage, the amount ofenergy stored exponentially increases (as torsional coil springs canstore energy in a nonlinear manner). In this manner, the torsional coilspring can act somewhat as a compressed gas chamber in terms of storingand releasing energy, but without the complexity of such pneumaticspring actuators.

FIGS. 6A-6G illustrate a clutched joint module 300 according to anexample of the present disclosure, which can be incorporated as, or inother words, can comprise a joint of a robotic assembly (e.g., 100,101).

The clutched joint module 300 can comprise a primary actuator 302, aquasi-passive elastic actuator 304 (FIG. 6B), and a clutch mechanism 306operatively coupled to each other, and each situated or arranged alongand operable about an axis of rotation 310. As further detailed below,an input member 308 a and an output member 308 b can be coupled torespective support members of the robotic assembly, which supportmembers are rotatable relative to each other about the axis of rotation310 of the joint, which can correspond to a degree of freedom of a humanjoint. For instance, the clutched joint module 300 can be incorporatedinto the robotic assembly 101 as clutched joint module 109 f of FIG. 4Cthat defines, at least in part, the joint 107 f comprising a shoulderjoint having a flexion/extension degree of freedom. Note that input andoutput members 308 a and 308 b are shown generically as members coupledto their respective components, but they can take many different formsand configurations of suitable input and output members or componentsthat are coupleable to robotic support members, for instance.

The primary actuator 302 can comprise a motor 312 and, optionally, atransmission, such as a first planetary transmission 314 and, furtheroptionally, a second transmission, such as second planetary transmission316 (FIGS. 6F and 6G). The motor 312 is operable to apply a primarytorque to the output member 308 b for rotation about the axis ofrotation 310, and the quasi-passive elastic actuator 304 (e.g., onehaving an elastic component in the form of a torsional coil spring) isselectively operable to store energy during a rotation of the jointmodule 300, and to release energy in the form of augmented torque to beapplied to the output member 308 b along with the primary torque appliedby the motor 312 (the two torques being combined to generate an outputvia the output member 308 b). The clutch mechanism 306 is operable toselectively control the quasi-passive elastic actuator 304 and thegeneration of the braking force or application of the augmented torque.Indeed, a braking force can be generated to restrict rotation of thejoint in some operational scenarios (e.g., scenarios where the primaryactuator is active or not active to produce a primary torque, but whererotation of the joint is desired), or an augmented torque can begenerated and applied in combination with a primary torque to assist inrotation of the output member and the joint, as discussed below.

The clutched joint module 300 can comprise a first support frame 315 a,a second support frame 315 b, and a third support frame 315 c fastenedtogether via various fasteners 317. The support frames 315 a-c canretain and support the various components discussed herein, such as themotor 312, the planetary transmissions 314 and 316, the clutch mechanism306, etc., as best shown on the cross sectional views of FIGS. 6F and6G.

As further detailed below, the quasi-passive elastic actuator 304 isoperable to selectively store energy or generate a braking force (whenin an elastic or semi-elastic configuration or mode or state) upon arotation of the input member 308 a (e.g., where the rotation is eitheractively carried out using the primary actuator, or passively carriedout, such as rotation of a joint under the influence of gravity of someother externally applied force that induces rotation) when the clutchmechanism 306 is in the engaged or semi-engaged state, and is operableto selectively release energy (also when in the elastic or semi-elasticconfiguration or mode or state) upon a rotation (in the same or adifferent direction as the rotation for storing the energy) of the inputmember 308 a, when the clutch mechanism 306 is in the engaged orsemi-engaged state, to apply the augmented torque to the output member308 b in parallel with a primary torque applied by the primary actuator302, in this case the motor 312. The quasi-passive elastic actuator 304is further operable in the inelastic state to neither store nor releaseenergy during rotation of the joint (inelastic configuration) when theclutch mechanism 306 is selectively caused to be in the disengagedstate. In this inelastic state, the input member 308 a is in “freeswing” relative to the output member 308 b, meaning that negligibleresistance is applied within the joint module 300 via the quasi-passiveelastic actuator 304 (so that the quasi-passive elastic actuator 304does not have a stiffness value that would restrict rotation of theinput member 308 a relative to the output member 308 b). The clutchmechanism 136 can also move from an engaged or semi-engaged state to adisengaged state to dissipate any stored energy (i.e., dissipate anybraking force generated, such as when the braking force no longerneeded). Thus, the quasi-passive elastic actuator 304 is selectivelyswitchable between the elastic state, the semi-elastic state, and theinelastic state via operation of the clutch mechanism 306. One advantageis that the quasi-passive elastic actuator 304 can be caused to apply,at select times, an augmented torque in parallel with the primary torqueapplied by the motor 312, which therefore applies a combined torque torotate the output member 308 b, thereby reducing the powerrequirements/demands of the motor 312. Thus, the selected motor 312 canbe of a smaller size and a lower power dissipation than otherwise wouldbe required by the robotic system without the assistance of theaugmented torque provided by the quasi-passive elastic actuator 304.

By “selective” it is meant that the clutched joint module can becontrolled in real-time, such as to vary a magnitude and timing of abraking force, vary a magnitude and timing of compression of the elasticcomponent of the quasi-passive actuator and the storing and releasing ofenergy therein, or vary a magnitude and timing of a primary torquegenerated by the primary actuator depending upon different operatingconditions, operating states, different demands of the robotic system,or as desired by the operator. Selective control can mean that thequasi-passive elastic actuator can be operated in conjunction with theprimary actuator all or some of the time or for a desired duration oftime. The term “selective” can also mean that one or more operatingparameters or the output performance of the clutched joint module can becontrolled and varied in real-time as needed or desired. Operatingparameters or output performance can include, but is/are not limited to,a magnitude of the augmented torque to be applied, a magnitude of thebraking force generated, the stiffness or elasticity of the elasticactuator, the zero or null point of actuation of the elastic actuator,and others.

In examples, “semi-engaged” can mean that the clutch mechanism isengaged, but not fully engaged nor disengaged, such that some slippageoccurs within the clutch mechanism (i.e., there is a less than a 1:1transfer of forces from the input of the clutch to the output of theclutch through the clutch mechanism, such that the clutch mechanism doesnot act as a rigid system). For example, in the case of the clutchmechanism having a plurality of plates, such as input and output plates,the semi-engaged state would mean that the plates are under acompression force sufficient to compress the plates together somedegree, but that some relative movement (i.e., slippage) occurs betweenthe plates (i.e., they are not completely locked up such that theyrotate together and movement between them is not completely restricted)and a friction force is generated between them (e.g., a usable brakingforce). The term “engaged state” as used herein can include thesemi-engaged state as these are also meant to describe at least apartially engaged state of the clutch mechanism, as well as to describethe clutch mechanism where the amount of slippage and thus the amount ofthe braking force (or augmented torque) is controllable and variablebetween the disengaged state where negligible braking force is generatedand fully engaged where the clutch models a rigid connection member.

In examples where the quasi-passive actuator is caused to enter a“semi-elastic state” or mode of operation, the quasi-passive elasticactuator can be actuated to partially compress the elastic or springcomponent of the quasi-passive elastic actuator to store, and be enabledto release, an amount of energy or be enabled to generate a magnitude ofa braking force that is less than what would otherwise be achieved ifthe quasi-passive elastic actuator were in a fully elastic state. Statedanother way, “semi-elastic” describes that state in which there is aless than 1:1 transfer of energy or forces, due to rotation of thejoint, to the quasi-passive elastic actuator coupled between the inputand output members (e.g., because the clutch mechanism is in thesemi-engaged state). “Semi-elastic,” as used herein, is not intended torefer to the inherent elastic property (i.e., the elasticity) of theelastic component of the quasi-passive elastic actuator, but merely to adegree of compression of the elastic component.

In one example, the motor 312 can comprise a high-performance PermanentMagnet Brushless DC motor (PM-BLDC). The motor 312 can comprise a stator320 and rotor 322 rotatable relative to each other (in a typical fashionfor commercially available frameless brushless motors). Thus, the motor312 of the primary actuator 302 comprises a cylindrical void 324 aboutthe central area of the rotor 322. Advantageously, the first planetarytransmission 314 can be positioned (at least partially) within thecylindrical void 324 of the motor 312, which provides a low-profile,compact geared motor configuration because the first planetarytransmission 314 and the motor 312 are packaged together, as shown anddescribed (and similar to motor 212 and planetary transmission 214 ofFIG. 5B). A transfer wheel 313 can be coupled to the rotor 322 viafasteners 319, so that rotation of the rotor 322 causes rotation of thetransfer wheel 313 about the axis of rotation 310.

In the present example, the first planetary transmission 314 cancomprise a 4:1 geared transmission, and can function as the planetarytransmission 214 discussed above. Thus, as with transmission 214 of FIG.5G, the first planetary transmission 314 can be nearly identical instructure and function as transmission 214. A sun gear 332 can bedisposed centrally between four planet gears 330 and along the axis ofrotation 310, with the sun gear 332 comprising teeth operable to engagethe teeth of each of the four planet gears 330 that rotate around thesun gear 332 and about an outer housing 326. The outer housing 326 canbe fastened to the second support frame 315 b to hold it stationary. Atthe output of the first planetary transmission 314, the planet gears 330are coupled to a carrier plate 334, which is coupled to a sun gear 346of the second planetary transmission 316. The second planetarytransmission 316 can be the same as or similar to the second planetarytransmission 216 of FIG. 5B, such that the output of the secondplanetary transmission 316 is coupled to the output member 308 b.

Therefore, upon receiving a control signal, the rotor 322 drives/rotatesthe transfer wheel 313, which rotates/drives the sun gear 332, whichdrives/rotates the carrier plate 334 (via planet gears 330). The carrierplate 334 then drives/rotates the sun gear 346 of the second planetarytransmission 316, which ultimately drives/rotates the output member 308b via the output of the second planetary transmission 316. Accordingly,the present example provides a 16:1 final drive transmission from themotor 312 to the output member 308 b. Other planetary transmission typesand gear reduction schemes can be used instead of a 4:1 transmission,such as a 3:1 planetary gear scheme. Note that output member 308 b isshown generically, but it could take other suitable forms andconfigurations for interfacing with the second planetary transmission316 and with a robotic support member, for example.

To reduce build height, as well as to provide other advantages, thefirst planetary transmission 314 can be configured to be positionedinside of the rotor of the motor 312. Depending on the motor selected,the inside diameter of the rotor can dictate the maximum outsidediameter of the planetary transmission. Once the planetary ring has beenconstrained by its outside diameter, there are a limited amount ofoptions for gear ratios and output torques available. The output ratiois determined from the ratio of the number of teeth on the ring gear tothe number of teeth on the sun gear. To obtain a higher reduction in thecompact design of the planetary unit, the sun gear diameter can bereduced, which generally corresponds to less power transmission. Thecapacity to transmit higher torques is reduced with the smaller sungear. A balance of reduction and strength can be found for a planetaryunit that will physically fit inside the motor rotor. By implementing ahelical cut gear, higher forces can be transmitted on the gear teeth orengagement features making the unit stronger. A wider tooth orengagement feature can also improve the load carrying capacity of thegear, however this can increase the weight as well. Multiple stages of aplanetary transmission can be cascaded (e.g., 314 and 316) to produceextremely high gear reduction in a relatively compact package,particularly one about the axis of rotation of the joint. In addition,the sun gear can make contact with several teeth simultaneously so thecontact ratio is much higher than a conventional spur gear transmission.In some examples, a single stage planetary transmission can achieveefficiency of around 97%. At higher RPM, gear noise can be an issue,especially for multiple stage planetary units. Another benefit of theplanetary transmission is the fact that the transmission can be locatedin-line with the motor, which allows for compact mounting configurationswithin the joint module 300 of the robot or robotic assembly.

As illustrated, the motor 312, the first and second planetarytransmissions 314 and 316, and the output member 308 b can each operateor rotate about substantially the same axis of rotation as the axis ofrotation 310 of the clutched quasi-passive actuator joint module 300(i.e., the axis of rotation of the corresponding joint of the robot orrobotic assembly), which axis of rotation in some cases, can alsocorrespond to the axis of rotation of a human joint, such as an operatorin an exoskeleton. Said another way, each axis of rotation of the motor312, the first and second planetary transmissions 314 and 316, and theoutput member 308 b can be arranged to be collinear or substantiallycollinear with the axis of rotation 310. This locates the mass of suchcomponents close or near to the axis of rotation of a particular joint,which further minimizes power requirements by the motor 312 to actuatethe joint.

With particular reference to FIGS. 6B, and as introduced above, thequasi-passive elastic actuator 304 is operable to apply an augmentedtorque to rotate the output member 308 b along with the primary torqueapplied by the primary actuator 302, or to generate a braking forcewithin the clutched joint module. Thus, the quasi-passive elasticactuator 304 is switchable between an elastic configuration, asemi-elastic configuration, and an inelastic configuration via operationof the clutch mechanism 306 for selectively controlling application ofthe augmented torque applied by the quasi-passive elastic actuator 304.

As in the example of FIGS. 5A-5E, the quasi-passive elastic actuator 304can comprise an elastic element in the form of a torsional coil spring305. One end of the torsional coil spring 305 can be coupled to atransfer shaft 307 and can be wound clockwise therefrom, and the otherend can be coupled to the input member 308 a (or to an intermediatecomponent coupled between the torsional coil spring 305 and a suitableinput member). The input member 308 a can comprise an annular ringsurrounding the torsional coil spring 305, or it can take other suitableforms as being coupled between the torsional coil spring 305 and arobotic support member. An output end of the transfer shaft 307 can becoupled to the transfer wheel 313, such that rotation of the transfershaft 307 (e.g., an applied augmented torque) causes rotation of thetransfer wheel 313, as detailed below. Note that the torsional coilspring 305 is only shown in FIG. 6B, but it will appreciated that it canbe disposed between the transfer wheel 313 and the clutch mechanism 306shown in the other Figures.

Turning to the clutch mechanism 306 of FIGS. 6D and 6E, anelectromagnetic clutch is disclosed to operate in series with thequasi-passive elastic actuator 304 (although it can be operated inparallel, as exemplified below). The clutch mechanism 306 can comprise aclutch housing 321 including a first clutch frame 323 a and a secondclutch frame 323 b coupled to each other and fastened to the firstsupport frame 315 a via fasteners 325. An annular collar 327 can besupported and surrounded by the first support frame 315 a, and cancomprise an L-shaped cross section (not shown) that receives anelectromagnetic device 329, which is retained by a collection of thesupport frames 315 a and 315 b and the annular collar 327. Theelectromagnetic device 329 can comprise an electromagnetic coil oractuator that is electrically coupled to a controller and a power source(which can be part of an onboard control system of the exoskeleton ofFIG. 4A).

A plate retention component 331 can be coupled to the second supportframe 323 b via fasteners 333 (e.g., radially disposed pins) seated inrecesses of the plate retention component 331. The plate frame component331 can be seated in an annular flange of the second support frame 323b. The clutch mechanism 306 can comprise a plurality of input plates 335a (e.g., four total) retained by the plate retention component 331. Inthis manner, the plate retention component 331 can comprise perimeterretaining features 337 (e.g., six recesses) formed annularly around aninside of the plate retention component 331 that receive and retainperimeter tabs or flanges 339 (six total) of each of the input plates335 a to restrict movement of the input plates 335 a relative to theclutch housing 321.

A plurality of output plates 335 b (e.g., four total) can each beslidably or frictionally interfaced (i.e., sandwiched between) withadjacent input plates 335 a in an alternating manner (FIG. 6E). Theoutput plates 335 b can each have a curvilinear perimeter that isslidably supported within curved inner surfaces of the plate retentioncomponent 331. Each output plate 335 b can comprise a central aperture341 that engages with a clutch output shaft 343 having a correspondingsize and shape (e.g., hexagon shaped central aperture and clutch outputshaft 343). Thus, rotation of the output plates 335 b causes concurrentrotation of the clutch output shaft 343. The clutch output shaft 343 iscoupled to the transfer shaft 307 that is coupled to the quasi-passiveelastic actuator 304 (FIG. 6B), such that rotation of the clutch outputshaft 343 causes rotation of the transfer shaft 307 (which is coupled tothe transfer wheel 313 discussed above). A cover plate 345 can becoupled to the plate retention component 331 to assist with retainingthe plates 335 a and 335 b.

The output plates 335 b can be comprised of a non-ferromagnetic materialwhile the input plates 335 b can be comprised of a ferromagneticmaterial. Upon receiving a clutch control signal (e.g., from acontroller), the electromagnetic actuator 329 is activated to apply anelectromagnetic field in a direction that tends to axially urge theinput plates 335 a along the axis of rotation 310, which therebycompresses the output plates 335 b between the respective input plates335 a, such that the plates 335 a and 335 b are restricted from movementrelative to the plate retention component 331 (which is attached to theclutch housing 321, and which is attached to the first support frame 315a). This is the engaged state of the clutch mechanism 306. Suchrestricted movement of the plates 335 a and 335 b thereby restrictsmovement of the clutch output shaft 343, which engages or otherwiseactivates the quasi-passive elastic actuator 304. Therefore, uponrotation of the input member 308 a (either via the primary actuator orvia application of an external force), and while the clutch mechanism306 is in this engaged state, the quasi-passive elastic actuator 304will therefore store energy or release energy (being in the elasticconfiguration), as described above, and depending upon the rotation ofthe input member 308 a (e.g., clockwise rotation of FIG. 6B storesenergy, while counterclockwise rotation releases energy, but opposingdirections are not to be limiting as the storage and release of energycan occur in the same rotational direction). This action of the clutchcan also be used to generate a braking force (i.e., compression of theelastic element generates a force that can be used to restrict movementof the output member relative to the input member). The electromagneticactuator 329 can be selectively operated and controlled to apply avariable magnetic field and a variable compression force, such that theclutch mechanism 306 operates between a disengaged state, a semi-engagedstate, and a fully engaged state to generate a variable braking force ora variable augmented torque. Indeed, in another aspect, with the clutchmechanism 306 operating in a semi-engaged state, movement between theinput plates 335 a and the output plates 335 b can be partiallyrestricted by the actuator 329 applying a smaller compression force tothe input and output plates 335 a, 335 b, such that some movementbetween the input plates 335 a and the output plates 335 b isfacilitated or caused to occur. In the engaged or the semi-engagedstate, the clutch mechanism 306 and the quasi-passive elastic actuator304 can function as a brake, or in other words, can provide a brakingforce operable to dissipate energy within the joint module, or these canfunction to apply an augmented torque to the output member. The degreeor magnitude of the compression force applied by the actuator 329 to theinput and output plates 335 a, 335 b can be dynamically controlled inreal-time by controlling or varying the amount of force generated andapplied by the actuator 329.

Conversely, upon receiving a clutch control signal, the electromagneticactuator 329 can be caused to place the clutched mechanism 306 in thedisengaged state. That is, a clutch control signal is received by theelectromagnetic actuator 329, such that the applied electric field isremoved, thereby releasing compression pressure applied by the inputplates 335 b. This allows the output plates 335 b to freely rotaterelative to the input plates 335 a.

This permits relatively “free swing” rotation of the input member 308 arelative to the output member 308 b, therefore placing the quasi-passiveelastic actuator 304 in its inelastic state. Thus, the quasi-passiveelastic actuator 304 exerts negligible resistance in this “free swing”mode, when the clutch mechanism is disengaged, so that the input andoutput members 308 a and 308 b can freely rotate relative to each otherwith minimal resistance. Furthermore, once stored, the energy can bedissipated at any time without being used either as a braking force orto apply an augmented torque, by disengaging the clutch mechanism 136.

When the clutch mechanism 306 is in the engaged or semi-engaged state,and the quasi-passive elastic actuator 304 is in the elastic orsemi-elastic state, the augmented torque can be applied by the torsionalcoil spring 305. This augmented torque can be translated via thetransfer shaft 307 to the sun gear 332 of the first planetarytransmission 314 (FIG. 6B), and so on (as described above), to rotatethe output member 308 b. For example, assume the torsional coil springis wound in the clockwise direction from the transfer shaft 307 (asshown), so that, upon a first clockwise rotation of the input member 308a about the axis of rotation 310, the torsional coil spring 305 storesenergy. Such rotational movement can be the result of a gait movement ofthe robotic assembly (e.g., of a lower body exoskeleton) that causes afirst robotic support member (e.g., 104 e) to rotate about a secondrobotic support member (e.g., 104 d), such as during a gait cyclebetween point B to C, as shown in FIG. 2 . Alternatively, suchrotational movement can be the result of a shoulder or elbow movement ofan exoskeleton during a certain task (e.g., downward movement of“push-ups” of an operator wearing an exoskeleton). Upon furtherrotation, or in the event of the disengagement of the clutch mechanism,such as in the counter-clockwise direction or depending upon the engagedstate of the clutch mechanism, the quasi-passive elastic actuator 304can release its stored energy, thereby transferring an augmented torqueto rotate the output member 308 b (as detailed above) or to apply abraking force. In one example, counterclockwise rotation can be aboutmodules 104 e and 104 d (and between points A to B of FIG. 2 ), or, inthe push-up example, such rotation can be during the upward movement ofthe push-up such that the energy stored during the downward push-upmovement is recovered/released during the upward motion of the push-up.

Concurrently, and upon such rotation, the motor 312 of the primaryactuator 302 can be operated to apply a primary toque (along with theaugmented torque) to rotate the output member 308 b about axis ofrotation 310 to actuate the joint module 300. Because the primary torqueapplied by the motor 312 is supplemented with the augmented torqueapplied by releasing stored/recovered energy via the quasi-passiveelastic actuator 304, the electric motor 312 can be selected from agroup of smaller (e.g., less power dissipation) motors than wouldotherwise be needed, which contributes to the compact configuration ofthe joint module 300, as also discussed above.

The electromagnetic actuator 356 can receive a clutch control signal tomove the clutch mechanism 306 to the disengaged state, as discussedabove. As a result, the quasi-passive elastic actuator 304 can releaseany stored energy, and in this state neither stores nor releases energy(i.e., as it is in the inelastic configuration).

Alternatively, the clutch output shaft 343 can be coupled to an input(i.e., sun gear 332) of the first planetary transmission 314, whichwould provide a parallel arrangement such as shown in FIG. 2B where theoutput of the quasi-passive actuator 304 (e.g., spring 129) isoperatively coupled between the motor and the gear train. In anotherexample of a parallel arrangement, the stator of the motor could becoupled to a body/housing of the clutch mechanism while one end of thequasi-passive actuator could be coupled to the rotor of the motor, andthe other end of the quasi-passive actuator could be coupled to asliding or rotating part of the clutch mechanism that may be disengagedor locked (i.e. coupled to the body of the clutch and at the same timeto the stator of the motor).

In one example discussed above, clutch mechanism 306 can be controlledas a binary device (i.e., the clutch mechanism 306 is either on/engagedor off/disengaged) when applying a compression force to compress theplates together, and when removing the compression force to releasecompression between the plates. Alternatively, the clutch mechanism 306can be configured and controlled as an analog device, meaning a variableelectromagnetic force can be applied by the electromagnetic actuator 329to compress the plates together to a varying degree to generate abraking force and to facilitate gradually storing energy ordissipating/releasing stored energy in a more controlled manner fordamping or braking purposes (i.e., the clutch mechanism 136 is in asemi-engaged state and the quasi-passive elastic actuator 134 is in asemi-elastic state). In one example operational scenario, the clutchmechanism 306 can be fully engaged or semi-engaged such that thequasi-passive elastic actuator 304 at least partially stores energy.This stored energy can function to generate a braking force that canrestrict rotation of the output member (e.g., such as in the case wherethe primary actuator is inactive and not producing a primary torque, yetrotation of the joint is still desired or needed (e.g., rotation of thejoint under the influence of gravity or in response to some externallyapplied force to the robotic system)), or it can be released as anaugmented torque to assist the primary actuator. Furthermore, in theevent of the release of the energy as an augmented torque, when thequasi-passive elastic actuator 304 is releasing energy in the elastic orsemi-elastic states (e.g., during a stance extension), the actuator 329can be operated to cause slight compression of the plates together togenerate a gradual “braking force” about the plates so that theaugmented torque can be discharged or applied in a controlled, gradualmanner. This can help to reduce the likelihood of applying a torquewithin the robotic system that may actuate the joint too quickly andwith too much velocity at an initial stage of actuation (which, in thecase of an exoskeleton type robotic system can cause discomfort to theoperator and can disrupt a desired fluid/natural movement of anexoskeleton limb). This may also be advantageous when lowering a loadwith the robotic system, where it is desirable to lower the load in acontrolled manner by controlling the amount of braking force applied byplates of one or more joint modules of the robotic system. Also in thecase of an exoskeleton, this may also be advantageous when an operatormoves from a crouching position while picking up a load (e.g., aperson), and the stance extension may need to be slower or morecontrolled. In such a case, the plates of clutch mechanisms of the hipand/or knee clutched joint modules may then be controlled as brakes tocontrollably dissipate stored energy released by the associatedquasi-passive elastic actuators.

Note that the quasi-passive elastic actuator 304 and the clutchmechanism 306 can be “coupled to” the input member 308 a as shown, or atany point between various components situated between the input andoutput members, such as between the motor 312 and the output member 308b (and between or adjacent any one of the planetary transmissions).

As further explanation, and to further illustrate, the multi-plateconfiguration of the clutch mechanism 306 can act as a brake. This isachieved by controlling the compression force applied to the input andoutput plates 335 a and 335 b, thus providing a beneficial energy savingmode of operation. For instance, by controlling the braking force, therobotic system can be caused to lower a load subject to gravity bysimultaneously controlling the brake force and the torque applied by theprimary actuator (which in some cases can be zero), thus providing avery efficient mode of operation. The controlled braking can also beused to store energy in the elastic component of the quasi-passiveelastic actuator. For example, an exoskeleton operator could lowerhim/herself to a squat position by letting part of his weight besupported by the exoskeleton while getting in the squat position. Inthis process, energy can be stored in the quasi-passive elasticactuator, while controlling the torque by controlling the braking force.At least some of the energy may then be recovered as the robotic devicemoves to the standing position, and additional torque may be provided,if required, by the primary actuator that would combine with the torqueproduced by the quasi-passive elastic actuator. In the latter examplethe clutch mechanism 306 can be used as a brake or as a clutch, or both.

In other examples, the quasi-passive elastic actuators discussed herein(i.e., 204 and 304) could be other types of springs, such as spiraltorsion springs, negator/constant torque or laminar torque springs, airsprings, planar spring, leaf springs, and the like.

Just as indicated above, various sensors, such as position sensors,force sensors, or both, can be operable within the joint module 300 todetermine and measure a positon or a force of the joint module 300, suchthat the quasi-passive actuator 304 can be engaged and disengaged asneeded or desired. In one example, a position sensor 361 can be coupledto a sensor frame 363 that is coupled to the first support frame 315 a.The position sensor 361 can assist to determine the position of theclutch output shaft 343, which assists to determine to the position ofthe input member 308 a relative to the output member 308 b. Otherposition sensors can be incorporated with the joint module 300 to assistwith such determination, such as described with reference to FIG. 5A-5E.

In one aspect, the quasi-passive elastic actuator 304 can act as agravity compensation mechanism to resist gravitational forces imposed onthe robotic assembly, such as on an arm of an exoskeleton, so that thehuman operator does not need to use energy to hold the robotic arm at adesired location or orientation. This is because the torsional coilspring, for instance, can exert a counter biasing force away from orthat acts against the gravitational pull (when the clutch is engaged) tomaintain a certain position of the joint and the robotic support memberscoupled thereto (as well as the relevant part of an operator, if any,such as in the case of an exoskeleton).

Note that spring stiffness of the quasi-passive elastic actuator 304 isa function of the size, shape, material, etc. of the torsional coilspring, for instance. Thus, the magnitude of stiffness for a given jointmodule is selectable (during manufacture and selection of the torsionalcoil spring) for mission-specific payloads and terrain-specific gaits(or other movements) while the clutch mechanism can be controlled andoperated to control when in time, or at what rotational positions/forcesduring the various rotational movements of the joint module 300 that thequasi-passive elastic actuator 304 is to be engaged for energyrecovery/release during the support phase (i.e., the elasticconfiguration), for instance, and when it is disengaged so as to enterthe free swinging phase (i.e., the inelastic configuration). Moreover,due to the nature of torsional coil springs, for instance, the greaterthe degree of rotation during energy storage, the amount of energystored exponentially increases (as torsional coil springs can storeenergy in a nonlinear manner). In this manner, the torsional coil springcan act somewhat as a compressed gas chamber in terms of storing andreleasing energy, but without the complexity of some pneumatic springactuators.

FIG. 7A illustrates a clutched actuator module 1130 in accordance withan example of the present disclosure, and FIG. 7B illustrates a primaryactuator of the clutched actuator module 1130. The clutched actuatorjoint module 1130 can comprise the clutch mechanism 206 and thequasi-passive elastic actuator 204 described with reference to FIGS.5A-5E positioned off-axis relative to an axis of rotation 1203 of aprimary actuator 1132. That is, an axis of rotation 1137 of componentsof the clutch mechanism 206 can be generally parallel to the axis ofrotation 1203 of the primary actuator 1132. Here, the output shaft 1208b can be coupled to an output of the clutch mechanism 206 (e.g., therotary transfer component 240 of FIG. 5D). A transmission device or belt1224 can be coupled to the clutch mechanism 206 via a splined ring gear(not shown) fastened or formed as part of the outer surface area of themovable engagement component 254 (see e.g., FIGS. 5D and 5E for a betterview and understanding). Alternatively, the transmission belt 1224 couldbe directly coupled to the output shaft 1208 b (e.g., the clutchmechanism 206 may need to be rotated 180 degrees from the orientationshown in FIG. 7A to accommodate such coupling between the belt 1224 andthe output shaft 1208 b). In either scenario, the transmission belt 1244can transfer a torque to the output shaft 1208 b to actuate the joint.Although not shown to scale, the left end of the output shaft 1208 b canbe rotatably interfaced to and through an aperture 1152 of a supportframe 1138 b, and then can be coupled to an output member that iscoupled to a robotic support member, or it can be coupled directly tothe robotic support member. Thus, as further detailed above regardingFIGS. 5A-5E, rotation of the input member 208 a causes rotation of themovable engagement component 254, which causes rotation of the rotarytransfer component, which causes rotation of the output shaft 1208 b torotate a particular joint of a robotic system, for instance.

More specifically regard this alternative configuration, the primaryactuator 1132 (e.g., a geared electric motor) is operable to apply atorque to the output member 1208 b (via the clutch mechanism, forinstance) for rotation about the axis of rotation 1137, and thequasi-passive elastic actuator 204 (e.g., a torsional coil spring) isselectively operable (via operation of the clutch) to apply an augmentedtorque to the output member 1208 b along with the torque applied by theprimary actuator 1132 to actuate the joint during a certain portion of agait movement (or other movement of an exoskeleton limb, such as the anupper body movement).

The clutch mechanism 206 can be structurally mounted to the primaryactuator 1132 by a first mounting plate 1138 a and a second mountingplate 1138 b, each positioned on either side so as to constrain theprimary actuator 1132 and the clutch mechanism 206 in a “sandwich”state. Although not shown here, the housing 215 b of the clutchmechanism 206 can have support members extending outwardly therefrom andcan be coupled and supported by the first and second mounting plates1138 a and 1138 b in a suitable manner.

Other suitable means of coupling the clutch mechanism 206 to the supportplates are possible and contemplated herein.

The first mounting plate 1138 a can be mounted to a housing mount 1140(that supports the primary actuator 1132) via a plurality of fasteners1142 (with spacers there between). The second mounting plate 1138 b ismounted to the other side of the housing mount 1140 via a plurality offasteners 1151.

The output shaft 1208 b (and/or an output member coupled to the shaft1208 b) can be a load transfer component that can comprise manydifferent shapes and forms, depending upon the particular application(e.g., exoskeleton, humanoid robot, robotic hand or arm). As such, thespecific configurations shown are not intended to be limiting in anyway. The output shaft 1208 b can comprise a robotic support memberinterface portion coupleable to a support structure of a roboticassembly, such as the exoskeleton of FIG. 4A.

The housing mount 1140 can comprise a first mount structure 1174 a and asecond mount structure 1174 b coupled to each other via fasteners. Thefirst and second mount structures 1174 a and 1174 b are fastenedtogether to house and structurally support many of the components of theprimary actuator 132. For instance, the primary actuator 1132 comprisesa motor 1178 (e.g., electric motor) that is seated in the first andsecond mount structures 1174 a and 1174 b. The motor 1178 can be ahigh-performance Permanent Magnet Brushless DC motor (PM-BLDC), whichcan be a variant of a frameless torque motor with winding optimized toachieve the desired maximum torque and speed while operating using a 48VDC supply and a high-performance COTS controller, such as motorMF0127-032 marketed by Allied Motion. The motor described above andshown in the drawings is not intended to be limiting in any way. Indeed,other motors suitable for use within the primary actuator 1132 arecontemplated herein, as are various other types of actuators, such ashydraulic actuators.

As further shown in FIG. 7B, the motor 1178 can comprise a stator 1180and rotor 1182 rotatable relative to each other (in a typical fashionfor commercially available frameless brushless motors). Note that theview of FIG. 7B is inverted relative to the view initially shown in FIG.7A of the primary actuator 1132. The motor 1178 can be configured tocomprise a central void 1184 about the central area of the motor 1178and surrounded by the rotor 1182. Advantageously, a planetarytransmission 1186 can be positioned within (entirely or partially) thecentral void 1184 (although other transmission types mentioned hereincould be utilized). This provides a low-profile geared motor state withhigh torque output for a relatively small electric motor, as exemplifiedelsewhere herein. It should be appreciated that the planetarytransmissions exemplified herein can be replaced (or supplemented with)other transmission types, such as harmonic, cycloidal, worm, belt/chain,crank, four-bar linkage, backhoe linkage, bell crank, and continuouslyvariable, for instance.

Planetary transmissions are well known and will not be discussed ingreat detail. However, in the present example the planetary transmission1186 can be configured as a 4:1 geared planetary transmission. Thus, inone example the planetary transmission 1186 can comprise an outer ring1190 engaged to four planet gears 1188 (one labeled) mounted about acarrier 1192, whereby the four planet gears 1188 have gear teeth thatengage with the gear teeth of a central sun gear (not visible from thisview). In the present example, the outer ring 1190 is stationary, as itis fastened to the first mount structure 1174 a via fasteners (notshown) through apertures around the outer ring 1190 and into threadedbores in the first mount structure 1174 a. A rotatable transfer wheel1198 is disposed on an outer side of the primary actuator 1132 adjacentthe second mount structure 1174 b, and is fastened to a drive collar1200 via perimeter fasteners. The drive collar 1200 is fastened or fixedto the rotor 1182 of the motor 1178. The transfer wheel 1198 is operableto transfer rotation from the rotor 1182 of the motor 1178 to the sungear (of transmission 1186) about the axis of rotation 1203 (FIG. 7A). Aspacer sleeve 1201 can be positioned adjacent the drive collar 1200 andbetween the outer ring 1190 of the planetary transmission 1186 and therotor 1182 to act as a support spacer between the planetary transmission1186 and the rotor 1182. Certain other details and the configuration ofFIGS. 7A and 7B if also described in U.S. patent application Ser. No.15/810,108, filed Nov. 12, 2017, which is incorporated by reference inits entirely herein.

The transfer wheel 1198 can comprise a central aperture 1204 thatsupports a transfer hub 1206 that is fastened to the transfer wheel 1198via fasteners. The transfer hub 1206 can have inner gear teeth (notshown) that can be engaged with outer gear teeth of the sun gear.Therefore, upon applying an electric field to the motor 1178, the rotor1182 rotates about axis 1203, which causes the transfer wheel 1198 torotate, which thereby causes the sun gear 1194 to rotate, all in a 1:1ratio. Upon rotation of the sun gear about axis of rotation 1203, theplanetary gears 1188 rotate around the sun gear, which causes thecarrier 1192 to rotate. An output shaft 1209 is secured to a centralportion 1211 of the carrier 1192, such that rotation of the carrier 1192causes rotation of the output shaft 1209 about axis 1203, which providesa 4:1 geared-down transmission arrangement from rotation of the rotor1182 to the output shaft 1209 via the planetary transmission 1186. Otherplanetary transmission types and gear reduction schemes can be usedinstead of a 4:1 transmission, such as a 3:1 or a 5:1 (or even greaterratios) planetary gear scheme.

To reduce build height, the planetary transmission 1186 can bepositioned inside of the rotor 1182 of the motor 1178. Depending on themotor selected, the inside diameter of the rotor will dictate themaximum outside diameter of the planetary transmission. Once theplanetary ring has been constrained by its outside diameter, there are alimited amount of options for gear ratios and output torques available.The output ratio is determined from the ratio of the number of teeth onthe ring gear to the number of teeth on the sun gear. To obtain a higherreduction in the compact design of the planetary unit, the sun geardiameter can be reduced, which generally corresponds to less powertransmission. The capacity to transmit higher torques is reduced with asmaller sun gear. A balance of reduction and strength can be determinedfor a planetary unit that will physically fit inside the motor rotor. Byimplementing a helical cut gear, higher forces can be transmitted on thegear teeth making the unit stronger. A wider tooth will also improve theload carrying capacity of the sun gear, however this increases theweight as well.

In addition, the sun gear makes contact with several teethsimultaneously so the contact ratio is much higher than a conventionalspur gear transmission. Another benefit of planetary gears is the factthat the transmission is in-line with the motor, which allows forcompact mounting states. Two of the 4:1 planetary units can be nestedtogether to produce a 16:1 final drive, for instance.

Thus, in one example using Allied Motion's MF0127-032 motor, it has aninside diameter of 3.3 inches, which means that a planetary transmissionof approximately 3.15 inches (or less) could be used and disposed in thecentral void of the motor. And, Matex's 75-4MLG12 planetary transmissioncan be incorporated, which is a 4:1 unit with a 2.95 inch outsidediameter having a 118 N-m peak torque, weighing just 500 grams. Suchplanetary transmission could be incorporated with a brushless motor asdiscussed herein to generate a compact configuration. Therefore, in theillustrated example of FIG. 7B, the output shaft 1209 applies arelatively higher torque at a low speed with very little noise andbacklash via the planetary transmission 1186, all in a compact formbecause the planetary transmission 1186 is housed within the void 1184of the brushless frameless electric motor 1178, for instance. It isnoted that the specific types of motors and planetary transmissionsdescribed herein are not intended to be limiting in any way, as will berecognized by those skilled in the art.

With continued reference to FIGS. 7A and 7B a free end 1210 of theoutput shaft 1192 extends through an aperture 1212 of the first mountstructure 1174 a. A tapered support collar 1214 surrounds and is coupledto the output shaft 1192 (a key and slot interface can be used to couplethe support collar 1214 to the output shaft 1192). The tapered supportcollar 1214 has an outer tapered surface that mates to an inner taperedsurface of a primary pulley 1216 (e.g., such as a Morse taper interface)to couple the output shaft 1192 to the primary pulley 1216 (a key andslot interface can be used to couple the support collar 1214 to theprimary pulley 1216). A first collar bearing can be positioned withinthe aperture 1212 (FIG. 7A) of the first mount structure 1174 a torotatably support the output shaft 1192, and a second collar bearing 218b can be positioned with an outer end of the primary pulley 1216 torotatably support the free end 1210 of the output shaft 1192.

In one example, a sensor plate 1220 can be fastened to an outer side ofthe second mount structure 1174 b, and has an aperture that supports aposition sensor 1222. The position sensor 1222 is adjacent the transferwheel 1198, which has an aperture through to the sun gear 1194 to allowthe position sensor 1222 to determine the position of the sun gear 1194,which can ultimately determine the rotational position of the outputshaft 1209, thereby providing the angular position of a knee or hipjoint, for instance. The position sensor 1222 can be any suitablesensor, such as a 13-bit hall-effect sensor. Additional positionssensors can be coupled to the system, and utilized to ultimatelydetermine the position of the joint. The particular position of anexoskeleton joint is relevant in determining and controlling actuationof the clutch mechanism to switch the quasi-passive elastic actuatorbetween the inelastic and elastic states, or to dynamically vary a zeropoint or position of the elastic actuator, as further discussed herein.

Upon rotation of the output shaft 1209 (in either rotational direction)by operating the motor 1178, the primary pulley 1216 rotates thetransmission belt 1224 that is coupled to the clutch mechanism 136 (oroutput shaft 1208 b), as discussed above, to provide a primary torque torotate the output shaft 1208 b to actuate a robotic joint, for instance.The transmission belt 1224 can be a Gates Poly Chain GT Carbonsynchronous belt, or other suitable belt. A belt tensioning device 1225(FIG. 7A) can be adjustably slidably coupled to a slot of the firstmounting plate 1138 a via a fastener, which is operable by a user with atool to slide the belt tensioning device 1225 toward or away from thebelt 1224 to tighten or loosen the belt 1224, as desired. In someexamples, various other torque-transmitting devices can replace theparticular configuration of the belt 1224, such as one or more belts orlinkages or gears or tendons (or combinations of such), and suchalternatives can be arranged to have an axis of rotation that isorthogonal to the axis of rotation 1203 of the primary actuator 1132 (orsome other angle other than parallel). And, various transmissions can bearranged to provide a relatively high gear reduction from input tooutput (e.g., 20:1, or more), or a relatively low gear reduction (e.g.,1:1), depending on the particular application. In some examples, suchvarious alternative torque-transmitting devices can allow the primaryactuator 1132 to be remotely located away from the output. For instance,the primary actuator 1132 could be located at a lower back area of anexoskeleton (e.g., FIG. 4A), while such alternative torque-transmittingdevice(s) could transfer the primary toque from the lower back area toan output member located adjacent the hip joint for actuating the hipjoint, for instance.

It should be appreciated that the clutch mechanism 306 and thequasi-passive elastic actuator 304 discussed regarding FIGS. 6A-6B couldreadily replace the clutch mechanism 206 and quasi-passive elasticactuator 204 of FIG. 7A, and can be mounted to the mounting plates in asimilar or different manner and can be operatively coupled to theprimary actuator 1132 via a transmission belt (or other transmission) ina similar way as described regarding FIGS. 7A and 7B.

It is also noted that the various functions and operational states ofthe clutch mechanism 206 and the quasi-passive elastic actuator 204described above with respect to FIGS. 5A-5E are applicable to theclutched joint module 1130. As such, these are not described again here,but those skilled in the art will recognize that upon reading thedescription above as it pertains to FIGS. 5A-5E that the clutched jointmodule 1130 can be operated in the same or a similar manner. Likewise,with the clutch mechanism 306 and the quasi-passive elastic actuator 304replacing the clutch mechanism 206 and quasi-passive elastic actuator204 of FIG. 7A the various functions and operational states of theclutch mechanism 306 and the quasi-passive elastic actuator 304described above with respect to FIGS. 6A-6G are applicable to theclutched joint module 1130. As such, these are not described again here,but those skilled in the art will recognize that upon reading thedescription above as it pertains to FIGS. 6A-6G that the clutched jointmodule 1130 can be operated in the same or a similar manner.

It is further noted that rotation of the joints (i.e., relative rotationbetween the input and output members) defined by the various clutchedjoint modules discussed herein can be in any direction (e.g., the samedirection, different directions) during the storing and releasing of theenergy, during the generation and application of a braking force, aswell as the disengagement of the clutch mechanism to facilitate freeswing of the joint. In other words, the clutch mechanism can be operatedto engage to store energy, to release energy, or to disengage tofacilitate free swing of the joint upon rotation of an associated jointin the same direction or in various different directions. This is thecase for all of the examples set forth in the present disclosure.

It is to be understood that the embodiments of the invention disclosedare not limited to the particular structures, process steps, ormaterials disclosed herein, but are extended to equivalents thereof aswould be recognized by those ordinarily skilled in the relevant arts. Itshould also be understood that terminology employed herein is used forthe purpose of describing particular embodiments only and is notintended to be limiting.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the present invention. Thus, appearancesof the phrases “in one embodiment” or “in an embodiment” in variousplaces throughout this specification are not necessarily all referringto the same embodiment.

As used herein, a plurality of items, structural elements, compositionalelements, and/or materials may be presented in a common list forconvenience. However, these lists should be construed as though eachmember of the list is individually identified as a separate and uniquemember. Thus, no individual member of such list should be construed as ade facto equivalent of any other member of the same list solely based ontheir presentation in a common group without indications to thecontrary. In addition, various embodiments and example of the presentinvention may be referred to herein along with alternatives for thevarious components thereof. It is understood that such embodiments,examples, and alternatives are not to be construed as de factoequivalents of one another, but are to be considered as separate andautonomous representations of the present invention.

Although the disclosure may not expressly disclose that some embodimentsor features described herein may be combined with other embodiments orfeatures described herein, this disclosure should be read to describeany such combinations that would be practicable by one of ordinary skillin the art. The user of “or” in this disclosure should be understood tomean non-exclusive or, i.e., “and/or,” unless otherwise indicatedherein.

Furthermore, the described features, structures, or characteristics maybe combined in any suitable manner in one or more embodiments. In thedescription, numerous specific details are provided, such as examples oflengths, widths, shapes, etc., to provide a thorough understanding ofembodiments of the invention. One skilled in the relevant art willrecognize, however, that the invention can be practiced without one ormore of the specific details, or with other methods, components,materials, etc. In other instances, well-known structures, materials, oroperations are not shown or described in detail to avoid obscuringaspects of the invention.

While the foregoing examples are illustrative of the principles of thepresent invention in one or more particular applications, it will beapparent to those of ordinary skill in the art that numerousmodifications in form, usage and details of implementation can be madewithout the exercise of inventive faculty, and without departing fromthe principles and concepts of the invention. Accordingly, it is notintended that the invention be limited, except as by the claims setforth below.

What is claimed is:
 1. A method for operating a robotic joint of arobotic system, the method comprising: selectively operating a clutchmechanism of a clutched joint module in an engaged state to cause aquasi-passive elastic actuator to enter an elastic state, the clutchedjoint module operating about and defining a joint of the robotic system;effecting a first rotation of the joint to cause the quasi-passiveelastic actuator to store energy during at least a portion of therotation of the joint; effecting a second rotation of the joint andcausing the stored energy from the quasi-passive elastic actuator to bereleased in the form of an augmented torque applied to an output memberof the clutched joint module; selectively operating the clutch mechanismin a disengaged state to cause the quasi-passive elastic actuator toenter an inelastic state; and effecting a third rotation of the joint,wherein the quasi-passive elastic actuator facilitates a free swing modeof the clutched joint module and the joint.
 2. The method of claim 1,further comprising selectively operating the clutch mechanism in theengaged and disengaged states to switch the quasi-passive elasticactuator between elastic and inelastic states, respectively.
 3. Themethod of claim 1, wherein effecting at least one of the first, secondor third rotation of the joint comprises operating a primary actuator toapply a primary torque to the output member.
 4. The method of claim 1,wherein effecting at least one of the first, second or third rotation ofthe joint comprises receiving a force applied about the joint from anexternal source.
 5. The method of claim 3, further comprisingtransferring the primary torque from the primary actuator to atransmission to actuate the clutched joint module.
 6. The method ofclaim 1, wherein the quasi-passive actuator comprises an elasticcomponent in the form of a torsional coil spring.
 7. The method of claim6, further comprising operating a clutch actuator of the clutchmechanism to cause a movable engagement component to engage one or moreengagement features of an engagement ring coupled to the torsional coilspring, thereby causing the clutch mechanism to enter the engaged stateto activate the quasi-passive elastic actuator.
 8. The method of claim1, wherein the clutch mechanism further comprises a semi-engaged state,the method further comprising selectively operating an electromagneticactuator to generate a variable electromagnetic field to apply avariable compression force to a plurality of plates in the clutchmechanism, thereby causing the clutch mechanism to enter one of theengaged or semi-engaged states where at least one of a braking force isgenerated or the augmented torque is applied to the output member.
 9. Amethod for configuring a clutched joint module for use within a roboticsystem, the method comprising: configuring an output member to couple toa first support member of a robotic system; configuring an input memberto couple to a second support member of the robotic system; configuringa primary actuator to apply a primary torque to the output member torotate the first and second support members relative to one anotherabout an axis of rotation of the clutched joint module; coupling aquasi-passive elastic actuator to the input member; configuring thequasi-passive elastic actuator, upon select operation of the clutchedjoint module, to apply an augmented torque to the output member thatcombines with the primary torque applied by the primary actuator torotate the output member about the axis of rotation; coupling a clutchmechanism to the primary actuator and the quasi-passive elasticactuator, such that the primary actuator comprises a primary axis ofrotation substantially collinear with the axis of rotation of theclutched joint module; and configuring the clutch mechanism, upon selectoperation of the clutched joint module, to operate in an engaged stateand a disengaged state, wherein, in the engaged state, the clutchmechanism operates to place the quasi-passive elastic actuator in anelastic state, and to facilitate application of the augmented torque.10. The method of claim 9, wherein in the disengaged state, the clutchmechanism operates to place the quasi-passive elastic actuator in aninelastic state.
 11. The method of claim 10, further comprisingconfiguring the clutch mechanism to comprise: a rotary transfercomponent coupled to the primary actuator; an engagement ring coupled toa torsional coil spring; a movable engagement component coupled to theinput member and engaged with the engagement ring; and a clutch actuatorcoupled to the movable engagement component, wherein the clutch actuatoris operable to translate the movable engagement component to engage therotary transfer component with the engagement ring to cause the clutchmechanism to function in the engaged state to facilitate application ofthe augmented torque upon a select operation of the clutched jointmodule.
 12. The method of claim 11, further comprising: configuring thetorsional coil spring to store energy upon a first rotation of the inputmember with the clutch mechanism in the engaged state, and the torsionalspring to release energy to apply the augmented torque upon a secondrotation of the input member with the clutch mechanism maintained in theengaged state; and configuring the clutch actuator, upon a thirdrotation of the input member, to disengage the moveable engagementcomponent from the rotary transfer component to disengage the clutchmechanism, and to place the quasi-passive elastic actuator in theinelastic state to facilitate removal of the augmented torque.
 13. Themethod of claim 11, further comprising configuring the clutch mechanismto comprise: a splined shaft rotatably coupled to the rotary transfercomponent and coupled to the torsional coil spring; and a splined collarcoupled to the splined shaft, wherein the clutch actuator is coupled tothe splined collar by a transmission belt operable to rotate the splinedcollar, thereby causing translation of the movable engagement componentbetween an engaged state and disengaged state with respect to the rotarytransfer component upon a select operation of the clutched joint module.14. The method of claim 11, further comprising configuring the primaryactuator to comprise an electric motor having a central void, andfurther comprising configuring the clutched joint module to comprise: afirst transmission at least partially disposed within the central void;and a second transmission operatively coupled between the firsttransmission and the output member.
 15. The method of claim 14, furthercomprising configuring the electric motor, the rotary transfercomponent, the engagement ring, the movable engagement component, andthe first and second transmissions to each rotate about the axis ofrotation of the clutched joint module upon a select operation of theclutched joint module.
 16. The method of claim 14, further comprisingcoupling the rotary transfer component to a rotor of the electric motorand to the first transmission, such that the rotary transfer componentis operable to transfer the primary torque from the electric motor tothe first transmission upon a select operation of the clutched jointmodule.